Physical random access channel enhanced transmission method, network device, and terminal

ABSTRACT

A physical random access channel enhanced transmission method, a network device, and a terminal are disclosed, where implementation of the terminal is used as an example, and the terminal includes: a processor, configured to determine level information of physical random access channel PRACH enhanced transmission; and to determine a first characteristic parameter that is of PRACH enhanced transmission and that is related to the determined level information of PRACH enhanced transmission, where the first characteristic parameter includes transmit power and a preamble format; and a transmitter, configured to perform PRACH enhanced sending according to the first characteristic parameter determined by the processor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/056,182, filed on Aug. 6, 2018, which is a continuation of U.S.patent application Ser. No. 15/588,504, filed on May 5, 2017, now U.S.Pat. No. 10,070,399, which is a continuation of U.S. patent applicationSer. No. 15/221,320, filed on Jul. 27, 2016, now U.S. Pat. No.9,674,796, which is a continuation of International Patent ApplicationNo. PCT/CN2014/071664, filed on Jan. 28, 2014. All of theafore-mentioned patent applications are hereby incorporated by referencein their entireties.

TECHNICAL FIELD

The present invention relates to the field of communicationstechnologies, and in particular, to a physical random access channelenhanced transmission method, a network device, and a terminal.

BACKGROUND

A resource in an LTE (Long Term Evolution) or LTE-A (LTE Advanced)system is classified into a radio frame (a system frame) in terms oftime, where one radio frame includes 10 subframes, a length of onesubframe is 1 ms, and one subframe includes two timeslots; and isclassified into a subcarrier in terms of frequency. A physical resourceblock (PRB) is defined as a timeslot in terms of time and 12 subcarriersin terms of frequency.

In a radio communications system, user equipment (UE)/terminal needs toestablish a connection to a network, and this process is generallyreferred to as a random access process. In the LTE or LTE-A system, therandom access process is classified into two types: a contention-basedrandom access process and a non-contention based random access process.The contention-based random access process includes four steps: Step 1.The UE sends a random access preamble (a preamble for short) to a basestation. Step 2. The base station returns a random access response tothe terminal. Step 3. Message 3 (Msg 3). Step 4. Contention resolutionmessage (Msg 4). The non-contention based random access process includesonly the first two steps.

In an LTE or LTE-A network with coverage enhancement, enhancedtransmission needs to be performed on a physical random access channel(PRACH), and PRACH enhanced transmission refers to resending, in arandom access process, a random access preamble according to an existingpreamble format. When existing LTE/LTE-A network coverage needs coverageenhancement of additional x dB (for example, x=15 or 20), actually,because distances between different UEs and the base station aredifferent, channel environments between the different UEs and the basestation are different, and path losses between the UEs and the basestation are also different, a required system coverage enhancement valuemay be a value in 0-x dB for the different UEs. To implement connectionestablishment between the different UEs and the network, quantities ofrepetition times required by the UEs to send a preamble are alsodifferent.

Currently, a solution to implementing PRACH enhanced transmission is asfollows: there are multiple repetition levels of PRACH enhancedtransmission for preamble resending, for example, repetition levels 1,2, and 3 of PRACH enhanced transmission. A quantity of repetition timesfor sending a preamble by UE at each repetition level is specified inadvance by the system or signaled. At different repetition levels ofPRACH enhanced transmission, quantities of repetition times for sendinga preamble by the UE are different. When a required system coverageenhancement value is larger, a path loss between the UE and the basestation is also larger, a repetition level that is of PRACH enhancedtransmission and that is required to be used by the UE to successfullycomplete a random access process is also higher, and the quantity ofrepetition times for sending the preamble is larger. At each repetitionlevel, the UE resends the random access preamble according to a quantityof repetition times for the repetition level.

For each repetition level of PRACH enhanced transmission, a resource setof PRACH enhanced transmission is specified in advance by the system orsignaled. The resource set of PRACH enhanced transmission includes oneor more resources of PRACH enhanced transmission. The resources of PRACHenhanced transmission include a code resource (a preamble), a timeresource, and a frequency resource that are used to send the preamble.The time resource and the frequency resource may be collectivelyreferred to as a time-frequency resource. During PRACH enhancedtransmission, the UE sends the preamble by using one repetition level ofPRACH enhanced transmission, and resends, according to a quantity ofrepletion times for the repetition level and according to an existingpreamble format, the preamble on a resource that is of PRACH enhancedtransmission and that is included in a resource set for the repetitionlevel.

For PRACH enhanced transmission, a time resource and/or a frequencyresource included in a resource set of PRACH enhanced transmission maybe the same as a time resource and/or a frequency resource for PRACHtransmission (PRACH transmission that does not need to be enhanced, anda preamble is sent according to an existing format without repetition).In PRACH enhanced transmission and PRACH transmission, resourcemultiplexing is performed in a code division multiplexing (CDM) manner,that is, the resource set of PRACH enhanced transmission and a resourceset of PRACH transmission include different code resources (preambles).The time resource and/or the frequency resource included in the resourceset of PRACH enhanced transmission may also be newly defined, and aredifferent from the time resource and/or the frequency resource of PRACHtransmission.

At each repetition level of PRACH enhanced transmission, resending apreamble by UE according to a quantity of repetition times for therepetition level is denoted as one preamble sending attempt. If the UEdoes not receive an RAR after completing one preamble sending attempt ata repetition level of PRACH enhanced transmission (not a highestrepetition level of PRACH enhanced transmission), the UE increases therepetition level of PRACH enhanced transmission by one level, andperforms a preamble resending attempt according to a quantity ofrepetition times for an increased repetition level of PRACH enhancedtransmission.

Transmit power P_(PRACH) for sending the random access preamble by theUE is obtained according to the following formula:P_(PRACH)=min{P_(CMAX,c)(i),PREAMBLE_RECEIVED_TARGET_POWER+PL_(c)}_[dBm], where min{ } indicates anoperation for calculating a minimum value, P_(CMAX,c)(i) is a maximumvalue of transmit power of the UE in a subframe whose number is i,PL_(c) is a value of a downlink path loss that is estimated by the UE,dBm is a power unit decibels per milliwatt, andPREAMBLE_RECEIVED_TARGET_POWER is preamble received target power and isobtained by calculatingpreambleInitialReceivedTargetPower+DELTA_PREAMBLE+(PREAMBLE_TRANSMISSION_COUNTER−1)*powerRampingStep,where preambleInitialReceivedTargetPower is preamble initial receivedtarget power, DELTA_PREAMBLE is a power offset value related to apreamble format, powerRampingStep is a power ramping step, andPREAMBLE_TRANSMISSION_COUNTER is a quantity of preamble transmissiontimes.

In the foregoing PRACH enhanced transmission method, if transmit poweris determined in the power calculation manner for each preamble sendingattempt performed by the UE, there is a problem of a power waste of UE.

SUMMARY

Embodiments of the present invention provide a physical random accesschannel enhanced transmission method, a network device, and a terminal,which are used to reduce power of a terminal.

A first aspect of the embodiments of the present invention provides aterminal, including:

a level determining unit, configured to determine level information ofphysical random access channel PRACH enhanced transmission;

a parameter determining unit, configured to determine a firstcharacteristic parameter that is of PRACH enhanced transmission and thatis related to the level information of PRACH enhanced transmission thatis determined by the level determining unit, where the firstcharacteristic parameter includes at least one of transmit power, apreamble format, and a time-frequency resource; and

a sending unit, configured to perform PRACH enhanced sending accordingto the first characteristic parameter determined by the parameterdetermining unit.

With reference to an implementation solution of the first aspect, in afirst possible implementation manner, the first characteristic parameterincludes the transmit power; and

the parameter determining unit is configured to determine the transmitpower of PRACH enhanced transmission according to a secondcharacteristic parameter corresponding to the level information of PRACHenhanced transmission, where the second characteristic parameter is atleast one of preamble initial received target power, a quantity ofpreamble transmission attempt times, a path loss, a path loss threshold,a power ramping step, a power offset value related to the preambleformat, and a power offset value related to the level information ofPRACH enhanced transmission.

With reference to the first possible implementation solution of thefirst aspect, in a second possible implementation manner, the parameterdetermining unit is configured to determine the transmit power of PRACHenhanced transmission according to the second characteristic parametercorresponding to the level information of PRACH enhanced transmission,where second characteristic parameters corresponding to different levelinformation of PRACH enhanced transmission are completely identical, orpartially identical, or completely different.

With reference to the first possible implementation solution of thefirst aspect, in a third possible implementation manner, the parameterdetermining unit is configured to determine, according to a thirdcharacteristic parameter corresponding to level information that is ofPRACH enhanced transmission and that is one level lower than the levelinformation of PRACH enhanced transmission, the at least one parameterincluded in the second characteristic parameter corresponding to thelevel information of PRACH enhanced transmission, where the thirdcharacteristic parameter is at least one of preamble initial receivedtarget power, a power ramping step, a fixed power offset value, and amaximum quantity of preamble transmission attempt times.

With reference to the third possible implementation solution of thefirst aspect, in a fourth possible implementation manner, the secondcharacteristic parameter includes the preamble initial received targetpower; and

the parameter determining unit is configured to: if the levelinformation of PRACH enhanced transmission is not the first level ofPRACH enhanced transmission, determine that: the preamble initialreceived target power corresponding to the level information of PRACHenhanced transmission is a sum of the preamble initial received targetpower and the power ramping step that are corresponding to the levelinformation that is of PRACH enhanced transmission and that is one levellower than the level information of PRACH enhanced transmission, or thepreamble initial received target power corresponding to the levelinformation of PRACH enhanced transmission is a fixed power offset valueplus a sum of the preamble initial received target power and the powerramping step that are corresponding to the level information that is ofPRACH enhanced transmission and that is one level lower than the levelinformation of PRACH enhanced transmission; or

if the level information of PRACH enhanced transmission is the firstlevel of PRACH enhanced transmission, determine that: the preambleinitial received target power corresponding to the level information ofPRACH enhanced transmission is preamble initial received target powerconfigured by a network device, or the preamble initial received targetpower corresponding to the level information of PRACH enhancedtransmission is a sum of preamble initial received target power and apower ramping step that are corresponding to PRACH transmission, or thepreamble initial received target power corresponding to the levelinformation of PRACH enhanced transmission is a fixed power offset valueplus a sum of preamble initial received target power and a power rampingstep that are corresponding to PRACH transmission.

With reference to the third possible implementation solution of thefirst aspect, in a fifth possible implementation manner, the secondcharacteristic parameter includes the quantity of preamble transmissionattempt times; and

the parameter determining unit is configured to: set an initial value ofthe quantity of preamble transmission attempt times corresponding to thelevel information of PRACH enhanced transmission to 1 plus the maximumquantity of preamble transmission attempt times corresponding to thelevel information that is of PRACH enhanced transmission and that is onelevel lower than the level information of PRACH enhanced transmission;or set an initial value of the quantity of preamble transmission attempttimes corresponding to the level information of PRACH enhancedtransmission to 1; or set an initial value of the quantity of preambletransmission attempt times corresponding to the level information ofPRACH enhanced transmission to 1 plus a maximum quantity of preambletransmission attempt times corresponding to PRACH transmission.

With reference to the first possible implementation solution of thefirst aspect, in a sixth possible implementation manner, the secondcharacteristic parameter includes the path loss or the path lossthreshold; and

the parameter determining unit is configured to: set the path losscorresponding to the level information of PRACH enhanced transmission toa lowest path loss for determining the level information of PRACHenhanced transmission; or set the path loss threshold corresponding tothe level information of PRACH enhanced transmission to a lowest pathloss threshold for determining the level information of PRACH enhancedtransmission.

With reference to the first possible implementation solution of thefirst aspect, in a seventh possible implementation manner, the secondcharacteristic parameter includes the power offset value related to thelevel information of PRACH enhanced transmission; and

the parameter determining unit is configured to: set the power offsetvalue related to the level information of PRACH enhanced transmission toa difference between a highest path loss or path loss threshold fordetermining the level information of PRACH enhanced transmission and apath loss estimated by a terminal UE; or set the power offset valuerelated to the level information of PRACH enhanced transmission to adifference between a sum of a lowest path loss or path loss thresholdfor determining the first level of PRACH enhanced transmission and aproduct that is obtained by multiplying the level information of PRACHenhanced transmission by a path loss step for determining the levelinformation of PRACH enhanced transmission and a path loss estimated bya terminal UE.

With reference to the first, the second, the third, the fourth, thefifth, the sixth, or the seventh possible implementation solution of thefirst aspect, in an eighth possible implementation manner, the parameterdetermining unit is further configured to: if the level information ofPRACH enhanced transmission is not highest level information of PRACHenhanced transmission, when the quantity of preamble transmissionattempt times corresponding to the level information of PRACH enhancedtransmission is equal to a sum of a difference between an initial valueof the quantity of preamble transmission attempt times corresponding tothe level information of PRACH enhanced transmission and 1 and aquantity of preamble transmission available attempt times correspondingto the level information of PRACH enhanced transmission, increase thelevel information of PRACH enhanced transmission by one level; or if thelevel information of PRACH enhanced transmission is not highest levelinformation of PRACH enhanced transmission, when the quantity ofpreamble transmission attempt times corresponding to the levelinformation of PRACH enhanced transmission is equal to a quantity ofpreamble transmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission, increase the levelinformation of PRACH enhanced transmission by one level; or if the levelinformation of PRACH enhanced transmission is highest level informationof PRACH enhanced transmission, when the quantity of preambletransmission attempt times corresponding to the level information ofPRACH enhanced transmission is equal to a sum of a difference between aninitial value of the quantity of preamble transmission attempt timescorresponding to the level information of PRACH enhanced transmissionand 1 and a quantity of preamble transmission available attempt timescorresponding to the level information of PRACH enhanced transmission,execute a backoff operation and perform a preamble resending attemptstarting from lowest level information of PRACH enhanced transmission,or execute a backoff operation and perform a preamble resending attemptby keeping the level information of PRACH enhanced transmission ashighest level information of PRACH enhanced transmission, or adjust abackoff parameter, or notify a higher layer that enhanced random accessfails; or if the level information of PRACH enhanced transmission ishighest level information of PRACH enhanced transmission, when thequantity of preamble transmission attempt times corresponding to thelevel information of PRACH enhanced transmission is equal to a quantityof preamble transmission available attempt times corresponding to thelevel information of PRACH enhanced transmission, execute a backoffoperation and perform a preamble resending attempt starting from lowestlevel information of PRACH enhanced transmission, or execute a backoffoperation and perform a preamble resending attempt by keeping the levelinformation of PRACH enhanced transmission as highest level informationof PRACH enhanced transmission, or adjust a backoff parameter, or notifya higher layer that enhanced random access fails.

With reference to the eighth possible implementation solution of thefirst aspect, in a ninth possible implementation manner, the parameterdetermining unit is further configured to determine that: quantitiesthat are of preamble transmission available attempt times and that arecorresponding to all level information of PRACH enhanced transmissionare the same, or quantities that are of preamble transmission availableattempt times and that are corresponding to at least two differentlevels of PRACH enhanced transmission are different.

With reference to the eighth possible implementation solution of thefirst aspect, in a tenth possible implementation manner, the parameterdetermining unit is configured to determine that: the quantity ofpreamble transmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission is configured by the networkdevice, or the quantity of preamble transmission available attempt timescorresponding to the level information of PRACH enhanced transmission ispredefined, or the quantity of preamble transmission available attempttimes corresponding to the level information of PRACH enhancedtransmission is determined according to a predefined rule.

With reference to an implementation solution of the first aspect, in aneleventh possible implementation manner, if the first characteristicparameter includes the transmit power,

the parameter determining unit is configured to: if the levelinformation of PRACH enhanced transmission is the n^(th) level of PRACHenhanced transmission, determine that: the transmit power of PRACHenhanced transmission is a maximum value of transmit power of a terminalUE, or the transmit power of PRACH enhanced transmission is a dedicatedpower value of the level information of PRACH enhanced transmission,where n is a positive integer.

With reference to the eleventh possible implementation solution of thefirst aspect, in a twelfth possible implementation manner, the parameterdetermining unit is configured to: determine the dedicated power valueof the level information of PRACH enhanced transmission according to apredefined value; or determine the dedicated power value of the levelinformation of PRACH enhanced transmission according to configurationperformed by a network device.

With reference to the eleventh or twelfth possible implementationsolution of the first aspect, in a thirteenth possible implementationmanner, the parameter determining unit is configured to determine thatdedicated power values of at least two different levels of PRACHenhanced transmission in dedicated power values of the level informationof PRACH enhanced transmission are different.

With reference to an implementation solution of the first aspect, in afourteenth possible implementation manner, if the first characteristicparameter includes the preamble format,

the parameter determining unit is configured to determine that: preambleformats related to all level information of PRACH enhanced transmissionare the same, or preamble formats related to at least two differentlevels of PRACH enhanced transmission are different.

With reference to the fourteenth possible implementation solution of thefirst aspect, in a fifteenth possible implementation manner, theparameter determining unit is configured to: in a process of determiningthat preamble formats related to at least two different levels of PRACHenhanced transmission are different, if there are N levels of PRACHenhanced transmission, determine that: the first N1 levels of PRACHenhanced transmission in the N levels of PRACH enhanced transmission arerelated to a first preamble format, and subsequent N−N1 levels of PRACHenhanced transmission in the N levels of PRACH enhanced transmission arerelated to a second preamble format, where both N and N1 are positiveintegers, N1 is less than N, and the first preamble format and thesecond preamble format are different.

With reference to the fifteenth possible implementation solution of thefirst aspect, in a sixteenth possible implementation manner, theparameter determining unit is configured to determine that the firstpreamble format and the second preamble format are preamble formats in apreamble format 1 and a preamble format 3.

With reference to an implementation solution of the first aspect, in aseventeenth possible implementation manner, the parameter determiningunit is configured to determine that a preamble format 4 is not used forPRACH enhanced transmission.

With reference to the fourteenth, the fifteenth, the sixteenth, or theseventeenth possible implementation solution of the first aspect, in aneighteenth possible implementation manner, the parameter determiningunit is configured to determine that: the used preamble format relatedto the determined level information of PRACH enhanced transmission ispredefined, or the preamble format related to the determined levelinformation of PRACH enhanced transmission is configured by a networkdevice.

With reference to an implementation solution of the first aspect, in anineteenth possible implementation manner, the first characteristicparameter includes the time-frequency resource; and

the parameter determining unit is configured to: determine thattime-frequency resources related to the first M1 levels of PRACHenhanced transmission in M adjacent levels of PRACH enhancedtransmission include a first time-frequency resource; and determine thattime-frequency resources related to subsequent M−M1 levels of PRACHenhanced transmission in the M adjacent levels of PRACH enhancedtransmission include a second time-frequency resource, where the firsttime-frequency resource and the second time-frequency resource aredifferent time-frequency resources, M and M1 are positive integers, andM1 is less than or equal to M.

A second aspect of the embodiments of the present invention provides aphysical random access channel enhanced transmission method, including:

determining level information of physical random access channel PRACHenhanced transmission;

determining a first characteristic parameter that is of PRACH enhancedtransmission and that is related to the level information of PRACHenhanced transmission, where the first characteristic parameter includesat least one of transmit power, a preamble format, and a time-frequencyresource; and

performing PRACH enhanced sending according to the first characteristicparameter.

With reference to an implementation solution of the second aspect, in afirst possible implementation manner, if the first characteristicparameter includes the transmit power, the determining a firstcharacteristic parameter that is of PRACH enhanced transmission and thatis related to the level information of PRACH enhanced transmissionincludes:

determining the transmit power of PRACH enhanced transmission accordingto a second characteristic parameter corresponding to the levelinformation of PRACH enhanced transmission, where the secondcharacteristic parameter is at least one of preamble initial receivedtarget power, a quantity of preamble transmission attempt times, a pathloss, a path loss threshold, a power ramping step, a power offset valuerelated to the preamble format, and a power offset value related to thelevel information of PRACH enhanced transmission.

With reference to the first possible implementation solution of thesecond aspect, in a second possible implementation manner, secondcharacteristic parameters corresponding to different level informationof PRACH enhanced transmission are completely identical, or partiallyidentical, or completely different.

With reference to the first possible implementation solution of thesecond aspect, in a third possible implementation manner, the at leastone parameter included in the second characteristic parametercorresponding to the level information of PRACH enhanced transmission isdetermined according to a third characteristic parameter correspondingto level information that is of PRACH enhanced transmission and that isone level lower than the level information of PRACH enhancedtransmission, where the third characteristic parameter is at least oneof preamble initial received target power, a power ramping step, a fixedpower offset value, and a maximum quantity of preamble transmissionattempt times.

With reference to the third possible implementation solution of thesecond aspect, in a fourth possible implementation manner, the secondcharacteristic parameter includes the preamble initial received targetpower, and a method for determining the second characteristic parametercorresponding to the level information of PRACH enhanced transmissionincludes:

if the level information of PRACH enhanced transmission is not the firstlevel of PRACH enhanced transmission, determining that: the preambleinitial received target power corresponding to the level information ofPRACH enhanced transmission is a sum of the preamble initial receivedtarget power and the power ramping step that are corresponding to thelevel information that is of PRACH enhanced transmission and that is onelevel lower than the level information of PRACH enhanced transmission,or the preamble initial received target power corresponding to the levelinformation of PRACH enhanced transmission is a fixed power offset valueplus a sum of the preamble initial received target power and the powerramping step that are corresponding to the level information that is ofPRACH enhanced transmission and that is one level lower than the levelinformation of PRACH enhanced transmission; or

if the level information of PRACH enhanced transmission is the firstlevel of PRACH enhanced transmission, determining that: the preambleinitial received target power corresponding to the level information ofPRACH enhanced transmission is preamble initial received target powerconfigured by a network device, or the preamble initial received targetpower corresponding to the level information of PRACH enhancedtransmission is a sum of preamble initial received target power and apower ramping step that are corresponding to PRACH transmission, or thepreamble initial received target power corresponding to the levelinformation of PRACH enhanced transmission is a fixed power offset valueplus a sum of preamble initial received target power and a power rampingstep that are corresponding to PRACH transmission.

With reference to the third possible implementation solution of thesecond aspect, in a fifth possible implementation manner, the secondcharacteristic parameter includes the quantity of preamble transmissionattempt times, and a method for determining the second characteristicparameter corresponding to the level information of PRACH enhancedtransmission includes:

setting an initial value of the quantity of preamble transmissionattempt times corresponding to the level information of PRACH enhancedtransmission to 1 plus the maximum quantity of preamble transmissionattempt times corresponding to the level information that is of PRACHenhanced transmission and that is one level lower than the levelinformation of PRACH enhanced transmission; or setting an initial valueof the quantity of preamble transmission attempt times corresponding tothe level information of PRACH enhanced transmission to 1; or setting aninitial value of the quantity of preamble transmission attempt timescorresponding to the level information of PRACH enhanced transmission to1 plus a maximum quantity of preamble transmission attempt timescorresponding to PRACH transmission.

With reference to the first possible implementation solution of thesecond aspect, in a sixth possible implementation manner, if the secondcharacteristic parameter includes the path loss or the path lossthreshold, a method for determining the second characteristic parametercorresponding to the level information of PRACH enhanced transmissionincludes:

setting the path loss corresponding to the level information of PRACHenhanced transmission to a lowest path loss for determining the levelinformation of PRACH enhanced transmission; or setting the path lossthreshold corresponding to the level information of PRACH enhancedtransmission to a lowest path loss threshold for determining the levelinformation of PRACH enhanced transmission.

With reference to the first possible implementation solution of thesecond aspect, in a seventh possible implementation manner, the secondcharacteristic parameter includes the power offset value related to thelevel information of PRACH enhanced transmission, and a method fordetermining the second characteristic parameter corresponding to thelevel information of PRACH enhanced transmission includes:

setting the power offset value related to the level information of PRACHenhanced transmission to a difference between a highest path loss orpath loss threshold for determining the level information of PRACHenhanced transmission and a path loss estimated by a terminal UE; or

setting the power offset value related to the level information of PRACHenhanced transmission to a difference between a sum of a lowest pathloss or path loss threshold for determining the first level of PRACHenhanced transmission and a product that is obtained by multiplying thelevel information of PRACH enhanced transmission by a path loss step fordetermining the level information of PRACH enhanced transmission and apath loss estimated by a terminal UE.

With reference to the first, the second, the third, the fourth, thefifth, the sixth, or the seventh possible implementation solution of thesecond aspect, in an eighth possible implementation manner, the methodfurther includes:

if the level information of PRACH enhanced transmission is not highestlevel information of PRACH enhanced transmission, when the quantity ofpreamble transmission attempt times corresponding to the levelinformation of PRACH enhanced transmission is equal to a sum of adifference between an initial value of the quantity of preambletransmission attempt times corresponding to the level information ofPRACH enhanced transmission and 1 and a quantity of preambletransmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission, increasing the levelinformation of PRACH enhanced transmission by one level; or

if the level information of PRACH enhanced transmission is not highestlevel information of PRACH enhanced transmission, when the quantity ofpreamble transmission attempt times corresponding to the levelinformation of PRACH enhanced transmission is equal to a quantity ofpreamble transmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission, increasing the levelinformation of PRACH enhanced transmission by one level; or

if the level information of PRACH enhanced transmission is highest levelinformation of PRACH enhanced transmission, when the quantity ofpreamble transmission attempt times corresponding to the levelinformation of PRACH enhanced transmission is equal to a sum of adifference between an initial value of the quantity of preambletransmission attempt times corresponding to the level information ofPRACH enhanced transmission and 1 and a quantity of preambletransmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission, executing a backoffoperation and performing a preamble resending attempt starting fromlowest level information of PRACH enhanced transmission, or executing abackoff operation and performing a preamble resending attempt by keepingthe level information of PRACH enhanced transmission as highest levelinformation of PRACH enhanced transmission, or adjusting a backoffparameter, or notifying a higher layer that enhanced random accessfails; or

if the level information of PRACH enhanced transmission is highest levelinformation of PRACH enhanced transmission, when the quantity ofpreamble transmission attempt times corresponding to the levelinformation of PRACH enhanced transmission is equal to a quantity ofpreamble transmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission, executing a backoffoperation and performing a preamble resending attempt starting fromlowest level information of PRACH enhanced transmission, or executing abackoff operation and performing a preamble resending attempt by keepingthe level information of PRACH enhanced transmission as highest levelinformation of PRACH enhanced transmission, or adjusting a backoffparameter, or notifying, by UE, a higher layer that enhanced randomaccess fails.

With reference to the eighth possible implementation solution of thesecond aspect, in a ninth possible implementation manner, quantitiesthat are of preamble transmission available attempt times and that arecorresponding to all level information of PRACH enhanced transmissionare the same, or quantities that are of preamble transmission availableattempt times and that are corresponding to at least two differentlevels of PRACH enhanced transmission are different.

With reference to the eighth possible implementation solution of thesecond aspect, in a tenth possible implementation manner, the quantityof preamble transmission available attempt times corresponding to thelevel information of PRACH enhanced transmission is configured by thenetwork device, or the quantity of preamble transmission availableattempt times corresponding to the level information of PRACH enhancedtransmission is predefined, or the quantity of preamble transmissionavailable attempt times corresponding to the level information of PRACHenhanced transmission is determined according to a predefined rule.

With reference to an implementation solution of the second aspect, in aneleventh possible implementation manner, if the first characteristicparameter includes the transmit power, the determining a firstcharacteristic parameter that is of PRACH enhanced transmission and thatis related to the level information of PRACH enhanced transmissionincludes:

if the level information of PRACH enhanced transmission is the n^(th)level of PRACH enhanced transmission, determining that: the transmitpower of PRACH enhanced transmission is a maximum value of transmitpower of a terminal UE, or the transmit power of PRACH enhancedtransmission is a dedicated power value of the level information ofPRACH enhanced transmission, where n is a positive integer.

With reference to the eleventh possible implementation solution of thesecond aspect, in a twelfth possible implementation manner, thededicated power value of the level information of PRACH enhancedtransmission is predefined; or the dedicated power value of the levelinformation of PRACH enhanced transmission is configured by a networkdevice.

With reference to the eleventh or twelfth possible implementationsolution of the second aspect, in a thirteenth possible implementationmanner, dedicated power values of at least two different levels of PRACHenhanced transmission are different.

With reference to an implementation solution of the second aspect, in afourteenth possible implementation manner, if the first characteristicparameter includes the preamble format, the determining a firstcharacteristic parameter that is of PRACH enhanced transmission and thatis related to the level information of PRACH enhanced transmissionincludes:

determining that: preamble formats related to all level information ofPRACH enhanced transmission are the same, or preamble formats related toat least two different levels of PRACH enhanced transmission aredifferent.

With reference to the fourteenth possible implementation solution of thesecond aspect, in a fifteenth possible implementation manner, thatpreamble formats related to at least two different levels of PRACHenhanced transmission are different includes:

if there are N levels of PRACH enhanced transmission, the first N1levels information of PRACH enhanced transmission in the N levels ofPRACH enhanced transmission are related to a first preamble format, andsubsequent N−N1 levels of PRACH enhanced transmission in the N levels ofPRACH enhanced transmission are related to a second preamble format,where both N and N1 are positive integers, N1 is less than N, and thefirst preamble format and the second preamble format are different.

With reference to the fifteenth possible implementation solution of thesecond aspect, in a sixteenth possible implementation manner, the firstpreamble format and the second preamble format are preamble formats in apreamble format 1 and a preamble format 3.

With reference to an implementation solution of the second aspect, in aseventeenth possible implementation manner, a preamble format 4 is notused for PRACH enhanced transmission.

With reference to the fourteenth, the fifteenth, the sixteenth, or theseventeenth possible implementation solution of the second aspect, in aneighteenth possible implementation manner, the preamble format relatedto the determined level information of PRACH enhanced transmission ispredefined, or the preamble format related to the determined levelinformation of PRACH enhanced transmission is configured by a networkdevice.

With reference to an implementation solution of the second aspect, in anineteenth possible implementation manner, if the first characteristicparameter includes the time-frequency resource, the determining a firstcharacteristic parameter that is of PRACH enhanced transmission and thatis related to the level information of PRACH enhanced transmissionincludes:

determining that time-frequency resources related to the first M1 levelsof PRACH enhanced transmission in M adjacent levels of PRACH enhancedtransmission include a first time-frequency resource; and determiningthat time-frequency resources related to subsequent M−M1 levels of PRACHenhanced transmission in the M adjacent levels of PRACH enhancedtransmission include a second time-frequency resource, where the firsttime-frequency resource and the second time-frequency resource aredifferent time-frequency resources, M and M1 are positive integers, andM1 is less than or equal to M.

A third aspect of the embodiments of the present invention provides anetwork device, including:

a parameter determining unit, configured to determine a firstcharacteristic parameter that is of PRACH enhanced transmission and thatis related to level information of physical random access channel PRACHenhanced transmission, where the first characteristic parameter includesat least one of a preamble format and a time-frequency resource; and

a receiving unit, configured to perform PRACH enhanced receivingaccording to the first characteristic parameter that is related to alllevel information of PRACH enhanced transmission and that is determinedby the parameter determining unit.

With reference to an implementation solution of the third aspect, in afirst possible implementation manner, the network device furtherincludes:

a sending unit, configured to: before the receiving unit performs PRACHenhanced receiving according to the first characteristic parameterrelated to all the level information of PRACH enhanced transmission,send, to UE, at least one of the following configuration information:preamble initial received target power, a quantity of preambletransmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission, and a dedicated power valueof the level information of PRACH enhanced transmission, so that the UEdetermines, according to the configuration information, transmit powerthat is of PRACH enhanced transmission and that is related to the levelinformation of PRACH enhanced transmission, or increase the levelinformation of PRACH enhanced transmission by one level, or execute abackoff operation and perform a preamble resending attempt starting fromlowest level information of PRACH enhanced transmission, or execute abackoff operation and perform a preamble resending attempt by keepingthe level information of PRACH enhanced transmission as highest levelinformation of PRACH enhanced transmission, or adjust a backoffparameter, or notify a higher layer that enhanced random access fails.

With reference to an implementation solution of the third aspect or thefirst possible implementation manner of the third aspect, in a secondpossible implementation manner, the parameter determining unit isfurther configured to determine that: quantities that are of preambletransmission available attempt times and that are corresponding to allthe level information of PRACH enhanced transmission are the same, orquantities that are of preamble transmission available attempt times andthat are corresponding to at least two different levels of PRACHenhanced transmission are different.

With reference to an implementation solution of the third aspect or thefirst possible implementation manner of the third aspect, in a thirdpossible implementation manner, the parameter determining unit isfurther configured to determine that dedicated power values of at leasttwo different levels of PRACH enhanced transmission in all the levelinformation of PRACH enhanced transmission are different.

With reference to an implementation solution of the third aspect, in afourth possible implementation manner, if the first characteristicparameter includes the preamble format, the parameter determining unitis configured to determine that: preamble formats related to all thelevel information of PRACH enhanced transmission are the same, orpreamble formats related to at least two different levels of PRACHenhanced transmission are different.

With reference to the fourth possible implementation manner of the thirdaspect, in a fifth possible implementation manner, the parameterdetermining unit is configured to: in a process of determining thatpreamble formats related to at least two different levels of PRACHenhanced transmission are different, if there are N levels of PRACHenhanced transmission, determine that: the first N1 levels of PRACHenhanced transmission in the N levels of PRACH enhanced transmission arerelated to a first preamble format, and subsequent N−N1 levels of PRACHenhanced transmission in the N levels information of PRACH enhancedtransmission are related to a second preamble format, where both N andN1 are positive integers, N1 is less than N, and the first preambleformat and the second preamble format are different.

With reference to the fifth possible implementation manner of the thirdaspect, in a sixth possible implementation manner, the parameterdetermining unit is configured to determine that the first preambleformat and the second preamble format are preamble formats in a preambleformat 1 and a preamble format 3.

With reference to an implementation solution of the third aspect, in aseventh possible implementation manner, the parameter determining unitis configured to determine that a preamble format 4 is not used forPRACH enhanced transmission.

With reference to the fourth, the fifth, the sixth, or the seventhpossible implementation solution of the third aspect, in an eighthpossible implementation manner, the parameter determining unit isconfigured to determine that the preamble format related to thedetermined level information of PRACH enhanced transmission ispredefined; or the sending unit included in the network device isconfigured to send, to UE, configuration information of the preambleformat related to the determined level information of PRACH enhancedtransmission.

With reference to an implementation solution of the third aspect, in aninth possible implementation manner, if the first characteristicparameter includes the time-frequency resource,

the parameter determining unit is configured to: determine thattime-frequency resources related to the first M1 levels of PRACHenhanced transmission in M adjacent levels of PRACH enhancedtransmission include a first time-frequency resource; and determine thattime-frequency resources related to subsequent M−M1 levels of PRACHenhanced transmission in the M adjacent levels of PRACH enhancedtransmission include a second time-frequency resource, where the firsttime-frequency resource and the second time-frequency resource aredifferent time-frequency resources, M and M1 are positive integers, andM1 is less than or equal to M.

A fourth aspect of the embodiments of the present invention provides aphysical random access channel enhanced transmission method, including:

determining a first characteristic parameter that is of PRACH enhancedtransmission and that is related to level information of physical randomaccess channel PRACH enhanced transmission, where the firstcharacteristic parameter includes at least one of a preamble format anda time-frequency resource; and

performing PRACH enhanced receiving according to the firstcharacteristic parameter related to all level information of PRACHenhanced transmission.

With reference to an implementation solution of the fourth aspect, in afirst possible implementation manner, before the performing PRACHenhanced receiving according to the first characteristic parameterrelated to all level information of PRACH enhanced transmission, themethod includes:

sending, to UE, at least one of the following configuration information:preamble initial received target power, a quantity of preambletransmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission, and a dedicated power valueof the level information of PRACH enhanced transmission, so that the UEdetermines, according to the configuration information, transmit powerthat is of PRACH enhanced transmission and that is related to the levelinformation of PRACH enhanced transmission, or increasing the levelinformation of PRACH enhanced transmission by one level, or executing abackoff operation and performing a preamble resending attempt startingfrom lowest level information of PRACH enhanced transmission, orexecuting a backoff operation and performing a preamble resendingattempt by keeping the level information of PRACH enhanced transmissionas highest level information of PRACH enhanced transmission, oradjusting a backoff parameter, or notifying a higher layer that enhancedrandom access fails.

With reference to an implementation solution of the fourth aspect or thefirst possible implementation manner of the fourth aspect, in a secondpossible implementation manner, quantities that are of preambletransmission available attempt times and that are corresponding to allthe level information of PRACH enhanced transmission are the same, orquantities that are of preamble transmission available attempt times andthat are corresponding to at least two different levels of PRACHenhanced transmission are different.

With reference to an implementation solution of the fourth aspect or thefirst possible implementation manner of the fourth aspect, in a thirdpossible implementation manner, dedicated power values of at least twodifferent levels of PRACH enhanced transmission are different.

With reference to an implementation solution of the fourth aspect, in afourth possible implementation manner, if the first characteristicparameter includes the preamble format, the determining a firstcharacteristic parameter that is of PRACH enhanced transmission and thatis related to level information of PRACH enhanced transmission includes:

determining that: preamble formats related to all the level informationof PRACH enhanced transmission are the same, or preamble formats relatedto at least two different levels of PRACH enhanced transmission aredifferent.

With reference to the fourth possible implementation manner of thefourth aspect, in a fifth possible implementation manner, that preambleformats related to at least two levels of PRACH enhanced transmissionare different includes:

if there are N levels of PRACH enhanced transmission, the first N1levels of PRACH enhanced transmission in the N levels of PRACH enhancedtransmission are related to a first preamble format, and subsequent N−N1levels of PRACH enhanced transmission in the N levels of PRACH enhancedtransmission are related to a second preamble format, where both N andN1 are positive integers, N1 is less than N, and the first preambleformat and the second preamble format are different.

With reference to the fifth possible implementation manner of the fourthaspect, in a sixth possible implementation manner, the first preambleformat and the second preamble format are preamble formats in a preambleformat 1 and a preamble format 3.

With reference to an implementation solution of the fourth aspect, in aseventh possible implementation manner, a preamble format 4 is not usedfor PRACH enhanced transmission.

With reference to the fourth, the fifth, the sixth, or the seventhpossible implementation solution of the fourth aspect, in an eighthpossible implementation manner, the preamble format related to thedetermined level information of PRACH enhanced transmission ispredefined; or configuration information of the preamble format relatedto the determined level information of PRACH enhanced transmission issent to UE.

With reference to an implementation solution of the fourth aspect, in aninth possible implementation manner, if the first characteristicparameter includes the time-frequency resource, the determining a firstcharacteristic parameter that is of PRACH enhanced transmission and thatis related to level information of PRACH enhanced transmission includes:

determining that time-frequency resources related to the first M1 levelsof PRACH enhanced transmission in M adjacent levels of PRACH enhancedtransmission include a first time-frequency resource; and determiningthat time-frequency resources related to subsequent M−M1 levels of PRACHenhanced transmission in the M adjacent levels of PRACH enhancedtransmission include a second time-frequency resource, where the firsttime-frequency resource and the second time-frequency resource aredifferent time-frequency resources, M and M1 are positive integers, andM1 is less than or equal to M.

A fifth aspect of the embodiments of the present invention provides adevice, configured as a half-duplex frequency division duplex receivingdevice, including:

a control unit, configured to: when the receiving device switches froman uplink subframe to a downlink subframe, control the receiving deviceto skip receiving data within a guard interval in a former part of thedownlink subframe, or to skip sending data within a guard interval in alater part of the uplink subframe.

With reference to an implementation solution of the fifth aspect, in afirst possible implementation manner, the control unit includes:

a guard interval determining unit, configured to determine the guardinterval according to a time for adjusting an operating frequency by afrequency oscillator and/or an uplink and downlink round-trippropagation delay.

A sixth aspect of the embodiments of the present invention provides anetwork device, including:

a sending control unit, configured to: control the network device toskip sending downlink data to a half-duplex frequency division duplexreceiving device in the first subframe preceding an uplink subframe,and/or control the network device to skip sending downlink data to thehalf-duplex frequency division duplex receiving device in the firstdownlink subframe following the uplink subframe.

A seventh aspect of the embodiments of the present invention provides aframe data transmission method, including:

when a half-duplex frequency division duplex receiving device switchesfrom an uplink subframe to a downlink subframe, skipping receiving, bythe receiving device, data within a guard interval in a former part ofthe downlink subframe, or skipping sending data within a guard intervalin a later part of the uplink subframe.

With reference to an implementation solution of the seventh aspect, in afirst possible implementation manner,

the guard interval is determined by using a time for adjusting anoperating frequency by a frequency oscillator and/or an uplink anddownlink round-trip propagation delay.

An eighth aspect of the embodiments of the present invention provides aframe data transmission method, including:

skipping sending, by a network device, downlink data to a half-duplexfrequency division duplex receiving device in the first subframepreceding an uplink subframe, and/or skipping sending, by the networkdevice, downlink data to the half-duplex frequency division duplexreceiving device in the first downlink subframe following the uplinksubframe.

It can be learned from the foregoing technical solutions that theembodiments of the present invention have the following advantages: afirst characteristic parameter is related to level information, and acharacteristic parameter used for PRACH enhanced sending can be rapidlyand accurately determined, which reduces power of a terminal.

BRIEF DESCRIPTION OF DRAWINGS

To describe the technical solutions in the embodiments of the presentinvention more clearly, the following briefly introduces theaccompanying drawings required for describing the embodiments.Apparently, the accompanying drawings in the following description showmerely some embodiments of the present invention, and a person ofordinary skill in the art may still derive other drawings from theseaccompanying drawings without creative efforts.

FIG. 1 is a schematic structural diagram of a terminal according to anembodiment of the present invention;

FIG. 2 is a schematic flowchart of a random access method according toan embodiment of the present invention;

FIG. 3 is a schematic flowchart of a method on a terminal side accordingto an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a network device accordingto an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a network device accordingto an embodiment of the present invention;

FIG. 6 is a schematic flowchart of a method on a network device sideaccording to an embodiment of the present invention;

FIG. 7 is a schematic structural diagram of a terminal according to anembodiment of the present invention;

FIG. 8 is a schematic structural diagram of a network device accordingto an embodiment of the present invention;

FIG. 9 is a schematic structural diagram of a terminal according to anembodiment of the present invention;

FIG. 10 is a schematic structural diagram of a network device accordingto an embodiment of the present invention;

FIG. 11 is a schematic structural diagram of a frame according to anembodiment of the present invention;

FIG. 12 is a schematic structural diagram of a frame according to anembodiment of the present invention;

FIG. 13 is a schematic structural diagram of a device according to anembodiment of the present invention;

FIG. 14 is a schematic structural diagram of a device according to anembodiment of the present invention;

FIG. 15 is a schematic structural diagram of a network device accordingto an embodiment of the present invention;

FIG. 16 is a schematic flowchart of a method according to an embodimentof the present invention;

FIG. 17 is a schematic flowchart of a method according to an embodimentof the present invention;

FIG. 18 is a schematic structural diagram of a device according to anembodiment of the present invention; and

FIG. 19 is a schematic structural diagram of a network device accordingto an embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

To make the objectives, technical solutions, and advantages of thepresent invention clearer, the following further describes the presentinvention in detail with reference to the accompanying drawings.Apparently, the described embodiments are merely a part rather than allof the embodiments of the present invention. All other embodimentsobtained by a person of ordinary skill in the art based on theembodiments of the present invention without creative efforts shall fallwithin the protection scope of the present invention.

A problem of a power waste of UE is specifically embodied as follows:

(1) In a case in which the UE increases a repetition level of PRACHenhanced transmission by one level, and performs a preamble sendingattempt according to a quantity of repetition times for an increasedrepetition level of PRACH enhanced transmission, if the UE has alreadyperformed multiple preamble sending attempts at an original repetitionlevel of PRACH enhanced transmission, and performs power ramping in eachpreamble sending attempt, that is, transmit power is increased bypowerRampingStep (dB), and random access is not completed after themultiple preamble sending attempts, the UE increases the originalrepetition level of PRACH enhanced transmission by one level. A downlinkpath loss PL_(c) estimated by the UE at the increased repetition levelof PRACH enhanced transmission is the same as that estimated at theoriginal repetition level, and if an initial value ofPREAMBLE_TRANSMISSION_COUNTER in the first preamble sending attempt is1, power of the first preamble sending attempt is the same as power ofthe first preamble sending attempt performed at the original repetitionlevel, and then power ramping is performed in a subsequent preamblesending attempt. Power of the first several preamble sending attemptsperformed by the UE at the increased repetition level of PRACH enhancedtransmission may not meet a requirement for successfully completing arandom access process, which causes a waste of the power of the firstseveral preamble sending attempts.

(2) In an LTE or LTE-A system with coverage enhancement, when a channelenvironment in which the UE is located is relatively poor, there is arelatively large error in a downlink path loss PL_(c) estimated by theUE, and in this case, there is also an error in transmit powercalculated by the UE, and if the power is relatively low, it is notnecessary for the UE to perform a preamble sending attempt by using therelatively low power, or if the power is relatively high, power forsending a preamble is wasted.

(3) If on a same time resource and a same frequency resource, the UEsends random access preambles at different repetition levels of PRACHenhanced transmission, that is, resource multiplexing is performed onthe random access preambles at the different repetition levels of PRACHenhanced transmission in a CDM manner, and if the random accesspreambles at the different repetition levels of PRACH enhancedtransmission use same transmit power, there is a near-far effect, thatis, path losses of the random access preambles at the differentrepetition levels of PRACH enhanced transmission are different, powerattenuation values when the preambles arrive at a base station are alsodifferent, and a preamble with a larger path loss is submerged by apreamble with a small path loss, which causes a preamble resendingattempt.

An embodiment of the present invention provides a terminal, configuredto implement physical random access channel PRACH enhanced transmission,where enhanced transmission may be retransmission, spread spectrumtransmission, or the like, and this embodiment of the present inventionis described by using retransmission as an example. A PRACH is a channelthat carries a preamble; PRACH enhanced transmission or PRACHtransmission may refer to enhanced transmission or transmission of achannel that carries a preamble, or may refer to enhanced transmissionor transmission of a preamble; transmission includes sending andreceiving. As shown in FIG. 1, the terminal includes a level determiningunit 101, a parameter determining unit 102, and a sending unit 103.

The level determining unit 101 is configured to determine levelinformation of physical random access channel PRACH enhancedtransmission.

In this embodiment of the present invention, the level information maybe any one of a level, a level index, an enhancement level, anenhancement level index, a repetition level, a repetition level index, aresource level, a resource level index, a resource set level, a resourceset level index, a resource set index, and a resource index.

The parameter determining unit 102 is configured to determine a firstcharacteristic parameter that is of PRACH enhanced transmission and thatis related to the level information of PRACH enhanced transmission thatis determined by the level determining unit 101.

In this embodiment of the present invention, the first characteristicparameter may be at least one of transmit power, a preamble format, anda time-frequency resource.

The sending unit 103 is configured to perform PRACH enhanced sendingaccording to the first characteristic parameter determined by theparameter determining unit 102.

This embodiment of the present invention is applied to an LTE or LTE-Asystem with coverage enhancement, and there are multiple repetitionlevels of PRACH enhanced transmission, for example, repetition levels 1,2, and 3 of PRACH enhanced transmission. Index numbering may beperformed on the multiple repetition levels, that is, repetition levelindexes. In another manner, there are multiple levels or multipleenhancement levels of PRACH enhanced transmission, and index numberingis performed on the multiple levels, that is, level indexes, or indexnumbering is performed on the multiple enhancement levels, that is,enhancement level indexes. The level information of PRACH enhancedtransmission is any one of the level, the level index, the enhancementlevel, the enhancement level index, the repetition level, and therepetition level index.

For each level of PRACH enhanced transmission, a quantity of repetitiontimes for sending a preamble by UE and a resource set of PRACH enhancedtransmission that are corresponding to each level of PRACH enhancedtransmission are specified in advance by the system or signaled. Theresource set of PRACH enhanced transmission includes one or moreresources of PRACH enhanced transmission. The resources of PRACHenhanced transmission include a code resource (a preamble), a timeresource, and a frequency resource that are used to send the preamble.The time resource and the frequency resource may be collectivelyreferred to as a time-frequency resource. If the UE determines the levelinformation of PRACH enhanced transmission, the UE resends, according toa quantity of repetition times corresponding to the determined levelinformation of PRACH enhanced transmission, a preamble on a resourcethat is of PRACH enhanced transmission and that is included in theresource set of PRACH enhanced transmission. For different levelinformation of PRACH enhanced transmission, quantities of repetitiontimes for sending a preamble by the UE are different. When a requiredsystem coverage enhancement value is larger, a path loss between the UEand a network device is also larger, level information that is of PRACHenhanced transmission and that is required to be used by the UE tosuccessfully complete a random access process is also higher, and thequantity of repetition times for sending the preamble is larger. Becausethere are multiple levels of PRACH enhanced transmission, there are alsomultiple resource sets of PRACH enhanced transmission, and the multipleresource sets are used by the UE to send the preamble according todifferent quantities of repetition times. A PRACH resource set may bereferred to as a resource set level of PRACH enhanced transmission, andone or more resources that are of PRACH enhanced transmission and thatare included in one resource set of PRACH enhanced transmission may becollectively referred to as one resource level of PRACH enhancedtransmission, and index numbering is separately performed on theresource set, the resource set level, the resource, and the resourcelevel that are of PRACH enhanced transmission, that is, a resource setindex, a resource set level index, a resource index, and a resourcelevel index that are of PRACH enhanced transmission. The levelinformation of PRACH enhanced transmission may also be any one of theresource level, the resource level index, the resource set level, theresource set level index, the resource set index, and the resourceindex. Index numbering is performed on the quantity of repetition timesfor sending the preamble by the UE, that is, an index of the quantity ofrepetition times. The level information of PRACH enhanced transmissionmay also be one of the quantity of repetition times and the index of thequantity of repetition times.

Optionally, the level information of PRACH enhanced transmission isdetermined according to the path loss between the network device and theUE. A base station or another network device presets a lowest path lossor path loss threshold and a highest path loss or path loss thresholdfor determining the level information of PRACH enhanced transmission,and the path loss between the network device and the UE is divided intoX ranges according to the lowest path loss or path loss threshold andthe highest path loss or path loss threshold, and each path loss rangeis corresponding to one level of PRACH enhanced transmission, so thatthe level information of PRACH enhanced transmission is determinedaccording to the lowest path loss or path loss threshold and the highestpath loss or path loss threshold. For example, a path loss or a pathloss threshold is preset to x0, x1, and x2, the path loss between thenetwork device and the UE is divided into three ranges, and the first,the second, and the third (or the 1st, the 2nd, and the 3rd) level ofPRACH enhanced transmission are determined, that is:

the first level of PRACH enhanced transmission: x0 dB<path loss≤x1 dB;

the second level of PRACH enhanced transmission: x1 dB<path loss≤x2 dB;and

the third level of PRACH enhanced transmission: path loss>x2.

For example, for the first level of PRACH enhanced transmission, thelowest path loss or path loss threshold and the highest path loss orpath loss threshold for determining the level information of PRACHenhanced transmission are x0 and x1 respectively. The lowest path lossor path loss threshold and the highest path loss or path loss thresholdand/or a value of X may be predefined or signaled by the network deviceto the UE. Index numbering is performed on the path loss range, that is,a path loss range index. The path loss may also be one of a requiredcoverage enhancement value, reference signal received power, referencesignal received quality, and channel quality information, and indexnumbering is performed on the coverage enhancement value, the referencesignal received power, the reference signal received quality, and achannel quality information range, that is, a coverage enhancement rangeindex, a reference signal received power range index, a reference signalreceived quality range index, and a channel quality information rangeindex. The level information of PRACH enhanced transmission may also beone of the coverage enhancement value, the coverage enhancement rangeindex, the path loss, the path loss range index, the reference signalreceived power, the reference signal received power range index, thereference signal received quality, the reference signal received qualityrange index, the channel quality information, and the channel qualityinformation range index.

In this embodiment of the present invention, the level determining unit101 may determine the level information of PRACH enhanced transmissionin multiple manners. The level determining unit 101 may also determinethat enhanced transmission is not to be performed on a PRACH, that is,determine that PRACH transmission is performed, where a preamble is sentaccording to an existing format without repetition. For example, levelinformation of PRACH transmission and/or the level information of PRACHenhanced transmission may be determined according to a path loss rangebetween the UE and a network side or another measurement parameter ormonitoring parameter that can reflect a path loss range; or it isdetermined that the level information of PRACH enhanced transmission isthe first (lowest) level of PRACH enhanced transmission; or it isdetermined that the level information of PRACH enhanced transmission islevel information obtained by increasing originally determined levelinformation of PRACH enhanced transmission by one level of PRACHenhanced transmission; or it is determined that PRACH transmission ischanged to the first level of PRACH enhanced transmission. A specificmanner for determining the level information of PRACH enhancedtransmission is not limited in this embodiment of the present invention.

One manner for determining the level information of PRACH transmissionand/or PRACH enhanced transmission is as follows: a part of the levelinformation of PRACH transmission and/or PRACH enhanced transmission isdetermined according to the path loss range between the UE and thenetwork side or the another measurement parameter or monitoringparameter that can reflect the path loss range, and other levelinformation of PRACH enhanced transmission is determined by the UE bysequentially performing an attempt from the level information of PRACHtransmission and/or from low level information of enhanced transmissionto high level information of enhanced transmission. If an attempt basedon the level information of PRACH transmission and/or the low levelinformation of enhanced transmission fails, the attempt is switched tobe performed based on an adjacent high level of enhanced transmission.For example, if the level information of PRACH enhanced transmissionincludes the first, the second, and the third level, PRACH transmissionis denoted as the 0^(th) level. If the path loss≤x3 dB, it is determinedthat the level information of PRACH transmission and/or PRACH enhancedtransmission is the 0^(th) level of PRACH transmission; if the pathloss>x4 dB, it is determined that the level information of PRACHtransmission and/or PRACH enhanced transmission is the third level ofPRACH enhanced transmission; if x3 dB<the path loss≤x4 dB, it is firstdetermined that the level information of PRACH transmission and/or PRACHenhanced transmission is the 0^(th) level of PRACH transmission (or thefirst level of PRACH enhanced transmission). If the determining fails,it is determined that the level information of PRACH transmission and/orPRACH enhanced transmission is the first level of a PRACH enhancedtransmission attempt (or the second level of PRACH enhancedtransmission), and so on.

Another manner for determining the level information of PRACHtransmission and/or PRACH enhanced transmission is as follows: it isdetermined that the level information of PRACH enhanced transmission isthe first (lowest) level of PRACH enhanced transmission. If the UEobtains main information by receiving an enhanced main informationblock, and/or obtains system information by receiving an enhanced systeminformation block, the UE performs preamble sending by using the firstlevel of PRACH enhanced transmission. If the UE fails to perform randomaccess by performing preamble sending by using the n^(th) level of PRACHenhanced transmission, the UE performs preamble sending by using the(n+1)^(th) level of PRACH enhanced transmission, where n is a positiveinteger. The enhanced main information block refers to a maininformation block that is re-sent in a radio frame for multiple times.The enhanced system information block includes one or more of anenhanced system information block of a system information block type 1,an enhanced system information block of a system information block typek, and an enhanced system information block of a system informationblock type m, where k and m are positive integers, and in particular,k=2. The enhanced system information block of the system informationblock type 1 refers to a system information block of the systeminformation block type 1 in a subframe #5 of a radio frame with an evennumber and/or a system information block that is of the systeminformation block type 1 and that is re-sent in another subframe. Theenhanced system information block of the system information block type krefers to a system information block that includes configurationinformation of PRACH enhanced transmission. At least one type ofconfiguration information in configuration information included in thesystem information block of the system information block type m is thesame as configuration information included in the system informationblock of the system information block type 1.

In this embodiment of the present invention, the first characteristicparameter is related to the level information, and a characteristicparameter used for PRACH enhanced sending can be rapidly and accuratelydetermined, which reduces power of a terminal.

Based on the three specific optional parameters included in the firstcharacteristic parameter, this embodiment of the present inventionproposes the following four solutions, which are specifically asfollows:

1. Optionally, the first characteristic parameter includes the transmitpower; and

the parameter determining unit 102 is configured to determine thetransmit power of PRACH enhanced transmission according to a secondcharacteristic parameter corresponding to the level information of PRACHenhanced transmission, where the second characteristic parameter is atleast one of preamble initial received target power, a quantity ofpreamble transmission attempt times, a path loss, a path loss threshold,a power ramping step, a power offset value related to the preambleformat, and a power offset value related to the level information ofPRACH enhanced transmission.

Optionally, the parameter determining unit 102 is configured todetermine the transmit power of PRACH enhanced transmission according tothe second characteristic parameter corresponding to the levelinformation of PRACH enhanced transmission, where second characteristicparameters corresponding to different level information of PRACHenhanced transmission are completely identical, or partially identical,or completely different.

Optionally, the parameter determining unit 102 is configured todetermine, according to a third characteristic parameter correspondingto level information that is of PRACH enhanced transmission and that isone level lower than the level information of PRACH enhancedtransmission, the at least one parameter included in the secondcharacteristic parameter corresponding to the level information of PRACHenhanced transmission, where the third characteristic parameter is atleast one of preamble initial received target power, a power rampingstep, a fixed power offset value, and a maximum quantity of preambletransmission attempt times.

Optionally, the second characteristic parameter includes the preambleinitial received target power; and

the parameter determining unit 102 is configured to: if the levelinformation of PRACH enhanced transmission is not the first level ofPRACH enhanced transmission, determine that: the preamble initialreceived target power corresponding to the level information of PRACHenhanced transmission is a sum of the preamble initial received targetpower and the power ramping step that are corresponding to the levelinformation that is of PRACH enhanced transmission and that is one levellower than the level information of PRACH enhanced transmission, or thepreamble initial received target power corresponding to the levelinformation of PRACH enhanced transmission is a fixed power offset valueplus a sum of the preamble initial received target power and the powerramping step that are corresponding to the level information that is ofPRACH enhanced transmission and that is one level lower than the levelinformation of PRACH enhanced transmission; or

if the level information of PRACH enhanced transmission is the firstlevel of PRACH enhanced transmission, determine that: the preambleinitial received target power corresponding to the level information ofPRACH enhanced transmission is preamble initial received target powerconfigured by a network device, or the preamble initial received targetpower corresponding to the level information of PRACH enhancedtransmission is a sum of preamble initial received target power and apower ramping step that are corresponding to PRACH transmission, or thepreamble initial received target power corresponding to the levelinformation of PRACH enhanced transmission is a fixed power offset valueplus a sum of preamble initial received target power and a power rampingstep that are corresponding to PRACH transmission.

Optionally, the second characteristic parameter includes the quantity ofpreamble transmission attempt times; and

the parameter determining unit 102 is configured to: set an initialvalue of the quantity of preamble transmission attempt timescorresponding to the level information of PRACH enhanced transmission to1 plus the maximum quantity of preamble transmission attempt timescorresponding to the level information that is of PRACH enhancedtransmission and that is one level lower than the level information ofPRACH enhanced transmission; or set an initial value of the quantity ofpreamble transmission attempt times corresponding to the levelinformation of PRACH enhanced transmission to 1; or set an initial valueof the quantity of preamble transmission attempt times corresponding tothe level information of PRACH enhanced transmission to 1 plus a maximumquantity of preamble transmission attempt times corresponding to PRACHtransmission.

Optionally, the second characteristic parameter includes the path lossor the path loss threshold; and

the parameter determining unit 102 is configured to: set the path losscorresponding to the level information of PRACH enhanced transmission toa lowest path loss for determining the level information of PRACHenhanced transmission; or set the path loss threshold corresponding tothe level information of PRACH enhanced transmission to a lowest pathloss threshold for determining the level information of PRACH enhancedtransmission.

Optionally, the second characteristic parameter includes the poweroffset value related to the level information of PRACH enhancedtransmission; and

the parameter determining unit 102 is configured to: set the poweroffset value related to the level information of PRACH enhancedtransmission to a difference between a highest path loss or path lossthreshold for determining the level information of PRACH enhancedtransmission and a path loss estimated by a terminal UE; or set thepower offset value related to the level information of PRACH enhancedtransmission to a difference between a sum of a lowest path loss or pathloss threshold for determining the first level of PRACH enhancedtransmission and a product that is obtained by multiplying the levelinformation of PRACH enhanced transmission by a path loss step fordetermining the level information of PRACH enhanced transmission and apath loss estimated by a terminal UE.

Optionally, the parameter determining unit 102 is further configured to:if the level information of PRACH enhanced transmission is not highestlevel information of PRACH enhanced transmission, when the quantity ofpreamble transmission attempt times corresponding to the levelinformation of PRACH enhanced transmission is equal to a sum of adifference between an initial value of the quantity of preambletransmission attempt times corresponding to the level information ofPRACH enhanced transmission and 1 and a quantity of preambletransmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission, increase the levelinformation of PRACH enhanced transmission by one level; or if the levelinformation of PRACH enhanced transmission is not highest levelinformation of PRACH enhanced transmission, when the quantity ofpreamble transmission attempt times corresponding to the levelinformation of PRACH enhanced transmission is equal to a quantity ofpreamble transmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission, increase the levelinformation of PRACH enhanced transmission by one level; or if the levelinformation of PRACH enhanced transmission is highest level informationof PRACH enhanced transmission, when the quantity of preambletransmission attempt times corresponding to the level information ofPRACH enhanced transmission is equal to a sum of a difference between aninitial value of the quantity of preamble transmission attempt timescorresponding to the level information of PRACH enhanced transmissionand 1 and a quantity of preamble transmission available attempt timescorresponding to the level information of PRACH enhanced transmission,execute a backoff operation and perform a preamble resending attemptstarting from lowest level information of PRACH enhanced transmission,or execute a backoff operation and perform a preamble resending attemptby keeping the level information of PRACH enhanced transmission ashighest level information of PRACH enhanced transmission, or adjust abackoff parameter, or notify a higher layer that enhanced random accessfails; or if the level information of PRACH enhanced transmission ishighest level information of PRACH enhanced transmission, when thequantity of preamble transmission attempt times corresponding to thelevel information of PRACH enhanced transmission is equal to a quantityof preamble transmission available attempt times corresponding to thelevel information of PRACH enhanced transmission, execute a backoffoperation and perform a preamble resending attempt starting from lowestlevel information of PRACH enhanced transmission, or execute a backoffoperation and perform a preamble resending attempt by keeping the levelinformation of PRACH enhanced transmission as highest level informationof PRACH enhanced transmission, or adjust a backoff parameter, or notifya higher layer that enhanced random access fails.

Further, the parameter determining unit 102 is further configured todetermine that: quantities that are of preamble transmission availableattempt times and that are corresponding to all level information ofPRACH enhanced transmission are the same, or quantities that are ofpreamble transmission available attempt times and that are correspondingto at least two levels of PRACH enhanced transmission are different.

Optionally, the parameter determining unit 102 is configured todetermine that: the quantity of preamble transmission available attempttimes corresponding to the level information of PRACH enhancedtransmission is configured by the network device, or the quantity ofpreamble transmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission is predefined, or thequantity of preamble transmission available attempt times correspondingto the level information of PRACH enhanced transmission is determinedaccording to a predefined rule.

2. Optionally, if the first characteristic parameter includes thetransmit power,

the parameter determining unit 102 is configured to: if the levelinformation of PRACH enhanced transmission is the n^(th) level of PRACHenhanced transmission, determine that: the transmit power of PRACHenhanced transmission is a maximum value of transmit power of a terminalUE, or the transmit power of PRACH enhanced transmission is a dedicatedpower value of the level information of PRACH enhanced transmission,where n is a positive integer.

Optionally, the parameter determining unit 102 is configured to:determine the dedicated power value of the level information of PRACHenhanced transmission according to a predefined value; or determine thededicated power value of the level information of PRACH enhancedtransmission according to configuration performed by a network device.

Optionally, the parameter determining unit 102 is configured todetermine that dedicated power values of at least two levels of PRACHenhanced transmission in dedicated power values of the level informationof PRACH enhanced transmission are different.

3. Optionally, if the first characteristic parameter includes thepreamble format,

the parameter determining unit 102 is configured to determine that:preamble formats related to all level information of PRACH enhancedtransmission are the same, or preamble formats related to at least twolevels of PRACH enhanced transmission are different.

Optionally, the parameter determining unit 102 is configured to: in aprocess of determining that preamble formats related to at least twolevels of PRACH enhanced transmission are different, if there are Nlevels of PRACH enhanced transmission, determine that: the first N1levels of PRACH enhanced transmission in the N levels of PRACH enhancedtransmission are related to a first preamble format, and subsequent N−N1levels of PRACH enhanced transmission in the N levels of PRACH enhancedtransmission are related to a second preamble format, where both N andN1 are positive integers, N1 is less than N, and the first preambleformat and the second preamble format are different.

Optionally, the parameter determining unit 102 is configured todetermine that the first preamble format and the second preamble formatare preamble formats in a preamble format 1 and a preamble format 3.

Optionally, the parameter determining unit 102 is configured todetermine that a preamble format 4 is not used for PRACH enhancedtransmission.

Optionally, the parameter determining unit 102 is configured todetermine that: the used preamble format related to the determined levelinformation of PRACH enhanced transmission is predefined, or thepreamble format related to the determined level information of PRACHenhanced transmission is configured by a network device.

4. Optionally, the first characteristic parameter includes thetime-frequency resource; and

the parameter determining unit 102 is configured to: determine thattime-frequency resources related to the first M1 levels of PRACHenhanced transmission in M adjacent levels of PRACH enhancedtransmission include a first time-frequency resource; and determine thattime-frequency resources related to subsequent M−M1 levels of PRACHenhanced transmission in the M adjacent levels of PRACH enhancedtransmission include a second time-frequency resource, where the firsttime-frequency resource and the second time-frequency resource aredifferent time-frequency resources, M and M1 are positive integers, andM1 is less than or equal to M.

Before a method in embodiments of the present invention is introduced,the following first describes a random access process of a terminal inthe prior art. As shown in FIG. 2, FIG. 2 shows a detailed descriptionof an optional random access process, which is specifically as follows:

201. UE sends a random access preamble (Msg 1) to a base station.

In this step, the UE sends the random access preamble to the basestation by using a PRACH (Physical Random Access Channel, physicalrandom access channel). The random access preamble includes a cyclicprefix (Cyclic Prefix, CP) part whose duration is T_(CP) and a sequencepart whose duration is T_(SEQ).

Currently, the random access preamble has five optional formats. For therandom access preamble in different formats, T_(SEQ) and T_(CP) havedifferent values, as shown in Table 1, where T_(s) indicates a timeunit, and generally Ts=1/(15000×2048) seconds. In a frequency domain,the PRACH occupies 1.08 MHz, that is, six PRBs.

TABLE 1 Random access preamble parameters Preamble format T_(CP) T_(SEQ)0 3168 · T_(s)   24576 · T_(s) 1 21024 · T_(s)    24576 · T_(s) 2 6240 ·T_(s) 2 · 24576 · T_(s) 3 21024 · T_(s)  2 · 24576 · T_(s)  4*  448 ·T_(s)    4096 · T_(s)

In an FDD (Frequency Division Duplex, frequency division duplex) system,random access may be performed by using one of preamble formats 0-3. Ina TDD (Time Division Duplex, time division duplex) system, in additionto the preamble formats 0-3, a preamble format 4 may also be used when atime length of an UpPTS (Uplink Pilot Time Slot, uplink pilot timeslot)configured by using a special subframe configuration is 4384 T_(s) and5120 T_(s). One preamble format is used in all random access processeswithin a cell, and the base station configures a physical random accesschannel configuration index (prach-ConfigurationIndex, packet randomaccess channel) for the UE (User Equipment, terminal) by using an SIB2(System Information Block Type2, system information block type 2) toindicate a preamble format used in the random access process.

There are 64 random access preambles in total within a cell, and in the64 preambles, a part of dedicated preambles are reserved fornon-contention based random access, and the remaining preambles are usedfor contention-based random access.

For the contention-based random access, the UE randomly selects apreamble from a set of preambles used for the contention-based randomaccess, and selects, from a predefined time resource and a predefinedfrequency resource, a resource for sending the selected preamble, andtherefore there is a possibility that multiple UEs simultaneously send asame preamble, and a subsequent contention resolution solution isrequired. For the non-contention based random access, the base stationconfigures, by using dedicated signaling, a dedicated preamble and atime resource and a frequency resource that are for sending thepreamble, and the UE performs random access by using the dedicatedpreamble.

Transmit power PPRACH for sending the random access preamble by the UEis obtained according to the following formula:PPRACH=min{P_(CMAX,c)(i), PREAMBLE_RECEIVED_TARGET_POWER+PL_(c)}_[dBm],where min{ } indicates an operation for calculating a minimum value,P_(CMAX,c)(i) is a maximum value of transmit power of the UE in asubframe whose number is i, PL_(c) is a value of a downlink path lossthat is estimated by the UE, dBm is a power unit decibels per milliwatt,and PREAMBLE_RECEIVED_TARGET_POWER is preamble received target power andis obtained by calculatingpreambleInitialReceivedTargetPower+DELTA_PREAMBLE+(PREAMBLE_TRANSMISSION_COUNTER−1)*powerRampingStep,where DELTA_PREAMBLE is a power offset value related to a preambleformat, powerRampingStep is a power ramping step, andPREAMBLE_TRANSMISSION_COUNTER is a quantity of preamble transmissiontimes.

preambleInitialReceivedTargetPower is preamble initial received targetpower and is a parameter configured by the base station for the UE byusing the SIB2, and DELTA_PREAMBLE is a power offset value related to apreamble format and is a fixed value. If the UE fails to complete onerandom access process, the UE resends the random access preamble, wherethe preamble may be sent for a maximum of preambleTransMax times, and amaximum quantity of preamble transmission times preambleTransMax is aparameter configured by using the SIB2. If in preambleTransMax times ofpreamble sending, the random access process is not successfullycompleted, the UE indicates a problem of random access to a higherlayer. An initial value of PREAMBLE_TRANSMISSION_COUNTER is 1, and avalue of the counter is increased by 1 each time preamble resending isperformed. When the UE resends the random access preamble, transmitpower is gradually increased in a ramping manner until a maximum valueP_(CMAX,c)(i) of the transmit power is reached. In each time of preamblesending, a value of increased power is a power ramping steppowerRampingStep, and this parameter is configured by the base stationfor the UE by using the SIB2.

202. The base station sends a random access response (Msg 2) to the UE.

After detecting the random access preamble, the base station sends therandom access response (Random Access Response, RAR). The random accessresponse RAR is carried over a PDSCH (Physical Downlink Shared Channel,physical downlink shared channel), and the PDSCH is scheduled by using aPDCCH (Physical Downlink Control Channel, physical downlink controlchannel) that is scrambled by using an RA-RNTI (Random Access RadioNetwork Temporary Identifier, random access radio network temporaryidentifier). The PDSCH includes an RAPID (Random Access Preamble Index,random access preamble index), which is used to indicate the randomaccess preamble detected by the base station. After sending the randomaccess preamble, the UE detects a PDCCH in each subframe within a randomaccess response window. After detecting the PDCCH that is scrambled byusing the RA-RNTI corresponding to the UE, the UE continues to performdemodulation for the PDSCH indicated by the PDCCH. If the RAPID includedin the PDSCH indicates the random access preamble selected by the UE,the PDSCH includes the RAR for the UE. If the UE does not receive theRAR for the UE within the random access response window, the UE resendsthe random access preamble. The RAR further includes information such asa timing alignment instruction, control information (UL grant) used toschedule message 3 (Msg3) data, and a temporary C-RNTI (Cell RadioNetwork Temporary Identifier, cell radio network temporary identifier).

203. The UE sends a message 3 (Msg 3) to the base station.

After successfully receiving the RAR for the UE within the random accessresponse window, the UE sends, by using a PUSCH (Physical Uplink SharedChannel, physical uplink shared channel), the message 3 (that is, Msg 3)in the random access process to the base station in a determinedsubframe that is after the RAR is received. The message 3 is scrambledby using the temporary C-RNTI (Cell Radio Network Temporary Identifier,cell radio network temporary identifier) included in the RAR, andincludes an identifier of the UE in this cell, which is used forcontention resolution.

As described in the foregoing, in the contention-based random access,multiple UEs simultaneously send a same preamble. In this case,different UEs receive a same RAR, to obtain a same temporary C-RNTI, andtherefore the message 3 is sent in a same time-frequency resource byusing the same temporary C-RNTI, which causes transmission collision ofthe message 3. If the base station cannot successfully decode themessage 3, the UE needs to retransmit the message 3, and if the basestation still cannot successfully decode the message 3 when a maximumquantity of retransmission times of the UE is reached, the UE resendsthe random access preamble. If the base station successfully decodes amessage 3 of UE, contention collision between UEs is to be resolved in adownlink message in step 4.

204. The base station sends a contention resolution message (Msg 4) tothe UE.

The UE receives the contention resolution message sent by the basestation, and completes the random access process. Within a time recordedby a timer for contention resolution, the UE detects the PDCCH and thecontention resolution message scheduled by the PDCCH, and if the UEreceives the contention resolution message scrambled by using theidentifier of the UE in this cell or the contention resolution messagethat includes the identifier of the UE in this cell, it is consideredthat the random access succeeds; if the UE has not yet received thecontention resolution message scrambled by using the identifier of theUE in this cell or the contention resolution message that includes theidentifier of the UE in this cell, when the timer expires, the UEresends the random access preamble.

MTC (machine type communication, machine type communication) means thatinformation about a physical world is acquired by deploying variousdevices that have particular sensing, computing, execution, andcommunication capabilities, and information transmission, collaboration,and processing are implemented by using a network, so as to implementinterconnection between a person and an object and interconnectionbetween objects. MTC may be combined with the Internet to implementremote sensing and control of an object, and is widely applied tomultiple fields such as smart grid, intelligent transportation,environmental protection, government work, public safety, smarthousehold, smart firefighting, industry monitoring, elderly nursing, andpersonal health. MTC development is known as the third wave of theinformation industry following a computer and the Internet, and isgreatly valued by a research institute and the industry.

A coverage area of a cell generally means the following: when the basestation sends a signal by using maximum transmit power, and if the UEcan correctly detect the signal sent by the base station with aparticular probability, it is considered that a position in which the UEis located is within the coverage area of the cell. The coverage area ofthe cell is affected by many factors, including a path loss of a radiosignal, sensitivity of a user's receiver, and the like. An importantapplication of an MTC service is a smart meter, and this type of smartmeter is generally installed in a basement of a house, or is isolated byusing a metal housing, or is installed in an old building with a thickwall. In this scenario, a path loss between the UE and the base stationis more severe.

When an LTE or LTE-A system supports the MTC service, LTE/LTE-A networkcoverage (coverage) needs to be enhanced. For example, coverageenhancement of additional 20 dB or 15 dB is performed based on existingLTE/LTE-A network coverage, to ensure that UE in a basement or in acondition in which channel quantity is poor can reliably communicatewith the base station.

To reduce power of UE, an embodiment of the present invention provides aphysical random access channel enhanced transmission method, as shown inFIG. 3, including the following steps:

301. Determine level information of physical random access channel PRACHenhanced transmission.

In this embodiment of the present invention, the level information maybe any one of a level, a level index, an enhancement level, anenhancement level index, a repetition level, a repetition level index, aresource level, a resource level index, a resource set level, a resourceset level index, a resource set index, and a resource index.

302. Determine a first characteristic parameter that is of PRACHenhanced transmission and that is related to the level information ofPRACH enhanced transmission.

In this embodiment of the present invention, the first characteristicparameter may be at least one of transmit power, a preamble format, anda time-frequency resource.

Based on the three specific optional parameters included in the firstcharacteristic parameter, this embodiment of the present inventionproposes the following four solutions, which are specifically asfollows:

1. Optionally, if the first characteristic parameter includes thetransmit power, the determining a first characteristic parameter that isof PRACH enhanced transmission and that is related to the levelinformation of PRACH enhanced transmission includes:

determining the transmit power of PRACH enhanced transmission accordingto a second characteristic parameter corresponding to the levelinformation of PRACH enhanced transmission, where the secondcharacteristic parameter is at least one of preamble initial receivedtarget power, a quantity of preamble transmission attempt times, a pathloss, a path loss threshold, a power ramping step, a power offset valuerelated to the preamble format, and a power offset value related to thelevel information of PRACH enhanced transmission.

Optionally, second characteristic parameters corresponding to differentlevel information of PRACH enhanced transmission are completelyidentical, or partially identical, or completely different.

Optionally, the at least one parameter included in the secondcharacteristic parameter corresponding to the level information of PRACHenhanced transmission is determined according to a third characteristicparameter corresponding to level information that is of PRACH enhancedtransmission and that is one level lower than the level information ofPRACH enhanced transmission, where the third characteristic parameter isat least one of preamble initial received target power, a power rampingstep, a fixed power offset value, and a maximum quantity of preambletransmission attempt times.

Optionally, the second characteristic parameter includes the preambleinitial received target power, and a method for determining the secondcharacteristic parameter corresponding to the level information of PRACHenhanced transmission includes:

if the level information of PRACH enhanced transmission is not the firstlevel of PRACH enhanced transmission, determining that: the preambleinitial received target power corresponding to the level information ofPRACH enhanced transmission is a sum of the preamble initial receivedtarget power and the power ramping step that are corresponding to thelevel information that is of PRACH enhanced transmission and that is onelevel lower than the level information of PRACH enhanced transmission,or the preamble initial received target power corresponding to the levelinformation of PRACH enhanced transmission is a fixed power offset valueplus a sum of the preamble initial received target power and the powerramping step that are corresponding to the level information that is ofPRACH enhanced transmission and that is one level lower than the levelinformation of PRACH enhanced transmission; or

if the level information of PRACH enhanced transmission is the firstlevel of PRACH enhanced transmission, determining that: the preambleinitial received target power corresponding to the level information ofPRACH enhanced transmission is preamble initial received target powerconfigured by a network device, or the preamble initial received targetpower corresponding to the level information of PRACH enhancedtransmission is a sum of preamble initial received target power and apower ramping step that are corresponding to PRACH transmission, or thepreamble initial received target power corresponding to the levelinformation of PRACH enhanced transmission is a fixed power offset valueplus a sum of preamble initial received target power and a power rampingstep that are corresponding to PRACH transmission.

Optionally, the second characteristic parameter includes the quantity ofpreamble transmission attempt times, and a method for determining thesecond characteristic parameter corresponding to the level informationof PRACH enhanced transmission includes:

setting an initial value of the quantity of preamble transmissionattempt times corresponding to the level information of PRACH enhancedtransmission to 1 plus the maximum quantity of preamble transmissionattempt times corresponding to the level information that is of PRACHenhanced transmission and that is one level lower than the levelinformation of PRACH enhanced transmission; or setting an initial valueof the quantity of preamble transmission attempt times corresponding tothe level information of PRACH enhanced transmission to 1; or setting aninitial value of the quantity of preamble transmission attempt timescorresponding to the level information of PRACH enhanced transmission to1 plus a maximum quantity of preamble transmission attempt timescorresponding to PRACH transmission.

Optionally, if the second characteristic parameter includes the pathloss or the path loss threshold, a method for determining the secondcharacteristic parameter corresponding to the level information of PRACHenhanced transmission includes:

setting the path loss corresponding to the level information of PRACHenhanced transmission to a lowest path loss for determining the levelinformation of PRACH enhanced transmission; or setting the path lossthreshold corresponding to the level information of PRACH enhancedtransmission to a lowest path loss threshold for determining the levelinformation of PRACH enhanced transmission.

Optionally, the second characteristic parameter includes the poweroffset value related to the level information of PRACH enhancedtransmission, and a method for determining the second characteristicparameter corresponding to the level information of PRACH enhancedtransmission includes:

setting the power offset value related to the level information of PRACHenhanced transmission to a difference between a highest path loss orpath loss threshold for determining the level information of PRACHenhanced transmission and a path loss estimated by a terminal UE; or

setting the power offset value related to the level information of PRACHenhanced transmission to a difference between a sum of a lowest pathloss or path loss threshold for determining the first level of PRACHenhanced transmission and a product that is obtained by multiplying thelevel information of PRACH enhanced transmission by a path loss step fordetermining the level information of PRACH enhanced transmission and apath loss estimated by a terminal UE.

Further, the method further includes:

if the level information of PRACH enhanced transmission is not highestlevel information of PRACH enhanced transmission, when the quantity ofpreamble transmission attempt times corresponding to the levelinformation of PRACH enhanced transmission is equal to a sum of adifference between an initial value of the quantity of preambletransmission attempt times corresponding to the level information ofPRACH enhanced transmission and 1 and a quantity of preambletransmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission, increasing the levelinformation of PRACH enhanced transmission by one level; or

if the level information of PRACH enhanced transmission is not highestlevel information of PRACH enhanced transmission, when the quantity ofpreamble transmission attempt times corresponding to the levelinformation of PRACH enhanced transmission is equal to a quantity ofpreamble transmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission, increasing the levelinformation of PRACH enhanced transmission by one level; or

if the level information of PRACH enhanced transmission is highest levelinformation of PRACH enhanced transmission, when the quantity ofpreamble transmission attempt times corresponding to the levelinformation of PRACH enhanced transmission is equal to a sum of adifference between an initial value of the quantity of preambletransmission attempt times corresponding to the level information ofPRACH enhanced transmission and 1 and a quantity of preambletransmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission, executing a backoffoperation and performing a preamble resending attempt starting fromlowest level information of PRACH enhanced transmission, or executing abackoff operation and performing a preamble resending attempt by keepingthe level information of PRACH enhanced transmission as highest levelinformation of PRACH enhanced transmission, or adjusting a backoffparameter, or notifying a higher layer that enhanced random accessfails; or

if the level information of PRACH enhanced transmission is highest levelinformation of PRACH enhanced transmission, when the quantity ofpreamble transmission attempt times corresponding to the levelinformation of PRACH enhanced transmission is equal to a quantity ofpreamble transmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission, executing a backoffoperation and performing a preamble resending attempt starting fromlowest level information of PRACH enhanced transmission, or executing abackoff operation and performing a preamble resending attempt by keepingthe level information of PRACH enhanced transmission as highest levelinformation of PRACH enhanced transmission, or adjusting a backoffparameter, or notifying, by UE, a higher layer that enhanced randomaccess fails.

Optionally, quantities that are of preamble transmission availableattempt times and that are corresponding to all level information ofPRACH enhanced transmission are the same, or quantities that are ofpreamble transmission available attempt times and that are correspondingto at least two levels of PRACH enhanced transmission are different.

Optionally, the quantity of preamble transmission available attempttimes corresponding to the level information of PRACH enhancedtransmission is configured by the network device, or the quantity ofpreamble transmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission is predefined, or thequantity of preamble transmission available attempt times correspondingto the level information of PRACH enhanced transmission is determinedaccording to a predefined rule.

2. Optionally, if the first characteristic parameter includes thetransmit power, the determining a first characteristic parameter that isof PRACH enhanced transmission and that is related to the levelinformation of PRACH enhanced transmission includes:

if the level information of PRACH enhanced transmission is the n^(th)level of PRACH enhanced transmission, determining that: the transmitpower of PRACH enhanced transmission is a maximum value of transmitpower of a terminal UE, or the transmit power of PRACH enhancedtransmission is a dedicated power value of the level information ofPRACH enhanced transmission, where n is a positive integer.

Optionally, the dedicated power value of the level information of PRACHenhanced transmission is predefined; or the dedicated power value of thelevel information of PRACH enhanced transmission is configured by anetwork device.

Optionally, dedicated power values of at least two levels of PRACHenhanced transmission are different.

3. Optionally, if the first characteristic parameter includes thepreamble format, the determining a first characteristic parameter thatis of PRACH enhanced transmission and that is related to the levelinformation of PRACH enhanced transmission includes:

determining that: preamble formats related to all level information ofPRACH enhanced transmission are the same, or preamble formats related toat least two levels of PRACH enhanced transmission are different.

Optionally, that preamble formats related to at least two levels ofPRACH enhanced transmission are different includes:

if there are N levels of PRACH enhanced transmission, the first N1levels of PRACH enhanced transmission in the N levels of PRACH enhancedtransmission are related to a first preamble format, and subsequent N−N1levels of PRACH enhanced transmission in the N levels of PRACH enhancedtransmission are related to a second preamble format, where both N andN1 are positive integers, N1 is less than N, and the first preambleformat and the second preamble format are different.

Optionally, the first preamble format and the second preamble format arepreamble formats in a preamble format 1 and a preamble format 3.

Optionally, a preamble format 4 is not used for PRACH enhancedtransmission.

Optionally, the preamble format related to the determined levelinformation of PRACH enhanced transmission is predefined, or thepreamble format related to the determined level information of PRACHenhanced transmission is configured by a network device.

4. Optionally, if the first characteristic parameter includes thetime-frequency resource, the determining a first characteristicparameter that is of PRACH enhanced transmission and that is related tothe level information of PRACH enhanced transmission includes:

determining that time-frequency resources related to the first M1 levelsof PRACH enhanced transmission in M adjacent levels of PRACH enhancedtransmission include a first time-frequency resource; and determiningthat time-frequency resources related to subsequent M−M1 levels of PRACHenhanced transmission in the M adjacent levels of PRACH enhancedtransmission include a second time-frequency resource, where the firsttime-frequency resource and the second time-frequency resource aredifferent time-frequency resources, M and M1 are positive integers, andM1 is less than or equal to M.

303. Perform PRACH enhanced sending according to the firstcharacteristic parameter.

This embodiment of the present invention is applied to an LTE or LTE-Asystem with coverage enhancement, and there are multiple repetitionlevels of PRACH enhanced transmission, for example, repetition levels 1,2, and 3 of PRACH enhanced transmission. Index numbering may beperformed on the multiple repetition levels, that is, repetition levelindexes. In another manner, there are multiple levels or multipleenhancement levels of PRACH enhanced transmission, and index numberingis performed on the multiple levels, that is, level indexes, or indexnumbering is performed on the multiple enhancement levels, that is,enhancement level indexes. The level information of PRACH enhancedtransmission is any one of the level, the level index, the enhancementlevel, the enhancement level index, the repetition level, and therepetition level index.

For each level of PRACH enhanced transmission, a quantity of repetitiontimes for sending a preamble by UE and a resource set of PRACH enhancedtransmission that are corresponding to each level of PRACH enhancedtransmission are specified in advance by the system or signaled. Theresource set of PRACH enhanced transmission includes one or moreresources of PRACH enhanced transmission. The resources of PRACHenhanced transmission include a code resource (a preamble), a timeresource, and a frequency resource that are used to send the preamble.The time resource and the frequency resource may be collectivelyreferred to as a time-frequency resource. If the UE determines the levelinformation of PRACH enhanced transmission, the UE resends, according toa quantity of repetition times corresponding to the determined levelinformation of PRACH enhanced transmission, a preamble on a resourcethat is of PRACH enhanced transmission and that is included in theresource set of PRACH enhanced transmission. For different levelinformation of PRACH enhanced transmission, quantities of repetitiontimes for sending a preamble by the UE are different. When a requiredsystem coverage enhancement value is larger, a path loss between the UEand a base station is also larger, level information that is of PRACHenhanced transmission and that is required to be used by the UE tosuccessfully complete a random access process is also higher, and thequantity of repetition times for sending the preamble is larger. Becausethere are multiple levels of PRACH enhanced transmission, there are alsomultiple resource sets of PRACH enhanced transmission, and the multipleresource sets are used by the UE to send the preamble according todifferent quantities of repetition times. A PRACH resource set may bereferred to as a resource set level of PRACH enhanced transmission, andone or more resources that are of PRACH enhanced transmission and thatare included in one resource set of PRACH enhanced transmission may becollectively referred to as one resource level of PRACH enhancedtransmission, and index numbering is separately performed on theresource set, the resource set level, the resource, and the resourcelevel that are of PRACH enhanced transmission, that is, a resource setindex, a resource set level index, a resource index, and a resourcelevel index that are of PRACH enhanced transmission. The levelinformation of PRACH enhanced transmission may also be any one of theresource level, the resource level index, the resource set level, theresource set level index, the resource set index, and the resourceindex. Index numbering is performed on the quantity of repetition timesfor sending the preamble by the UE, that is, an index of the quantity ofrepetition times. The level information of PRACH enhanced transmissionmay also be one of the quantity of repetition times and the index of thequantity of repetition times.

Optionally, the level information of PRACH enhanced transmission isdetermined according to the path loss between the base station and theUE. The base station or another network device presets a lowest pathloss or path loss threshold and a highest path loss or path lossthreshold for determining the level information of PRACH enhancedtransmission, and the path loss between the base station and the UE isdivided into X ranges according to the lowest path loss or path lossthreshold and the highest path loss or path loss threshold, and eachpath loss range is corresponding to one level of PRACH enhancedtransmission, so that the level information of PRACH enhancedtransmission is determined according to the lowest path loss or pathloss threshold and the highest path loss or path loss threshold. Forexample, a path loss or a path loss threshold is preset to x0, x1, andx2, the path loss between the base station and the UE is divided intothree ranges, and the first, the second, and the third (or the 1st, the2nd, and the 3rd) level of PRACH enhanced transmission are determined,that is:

the first level of PRACH enhanced transmission: x0 dB<path loss≤x1 dB;

the second level of PRACH enhanced transmission: x1 dB<path loss≤x2 dB;and

the third level of PRACH enhanced transmission: path loss>x2.

For example, for the first level of PRACH enhanced transmission, thelowest path loss or path loss threshold and the highest path loss orpath loss threshold for determining the level information of PRACHenhanced transmission are x0 and x1 respectively. The lowest path lossor path loss threshold and the highest path loss or path loss thresholdand/or a value of X may be predefined or signaled by the base station tothe UE. Index numbering is performed on the path loss range, that is, apath loss range index. The path loss may also be one of a requiredcoverage enhancement value, reference signal received power, referencesignal received quality, and channel quality information, and indexnumbering is performed on the coverage enhancement value, the referencesignal received power, the reference signal received quality, and achannel quality information range, that is, a coverage enhancement rangeindex, a reference signal received power range index, a reference signalreceived quality range index, and a channel quality information rangeindex. The level information of PRACH enhanced transmission may also beone of the coverage enhancement value, the coverage enhancement rangeindex, the path loss, the path loss range index, the reference signalreceived power, the reference signal received power range index, thereference signal received quality, the reference signal received qualityrange index, the channel quality information, and the channel qualityinformation range index.

In step 301 in this embodiment of the present invention, the levelinformation of PRACH enhanced transmission may be determined in multiplemanners. In step 301, it may also be determined that enhancedtransmission is not to be performed on a PRACH, that is, it isdetermined that PRACH transmission is performed, where a preamble issent according to an existing format without repetition. For example,level information of PRACH transmission and/or the level information ofPRACH enhanced transmission may be determined according to a path lossrange between the UE and a network side or another measurement parameteror monitoring parameter that can reflect a path loss range; or it isdetermined that the level information of PRACH enhanced transmission isthe first (lowest) level of PRACH enhanced transmission; or it isdetermined that the level information of PRACH enhanced transmission islevel information obtained by increasing originally determined levelinformation of PRACH enhanced transmission by one level of PRACHenhanced transmission; or it is determined that PRACH transmission ischanged to the first level of PRACH enhanced transmission. A specificmanner for determining the level information of PRACH enhancedtransmission is not limited in this embodiment of the present invention.

One manner for determining the level information of PRACH transmissionand/or PRACH enhanced transmission is as follows: a part of the levelinformation of PRACH transmission and/or PRACH enhanced transmission isdetermined according to the path loss range between the UE and thenetwork side or the another measurement parameter or monitoringparameter that can reflect the path loss range, and other levelinformation of PRACH enhanced transmission is determined by the UE bysequentially performing an attempt from the level information of PRACHtransmission and/or from low level information of enhanced transmissionto high level information of enhanced transmission. If an attempt basedon the level information of PRACH transmission and/or the low levelinformation of enhanced transmission fails, the attempt is switched tobe performed based on an adjacent high level of enhanced transmission.For example, if the level information of PRACH enhanced transmissionincludes the first, the second, and the third level, PRACH transmissionis denoted as the 0^(th) level. If the path loss≤x3 dB, it is determinedthat the level information of PRACH transmission and/or PRACH enhancedtransmission is the 0^(th) level of PRACH transmission; if the pathloss>x4 dB, it is determined that the level information of PRACHtransmission and/or PRACH enhanced transmission is the third level ofPRACH enhanced transmission; if x3 dB<the path loss≤x4 dB, it is firstdetermined that the level information of PRACH transmission and/or PRACHenhanced transmission is the 0^(th) level of PRACH transmission (or thefirst level of PRACH enhanced transmission). If the determining fails,it is determined that the level information of PRACH transmission and/orPRACH enhanced transmission is the first level of a PRACH enhancedtransmission attempt (or the second level of PRACH enhancedtransmission), and so on. In this embodiment of the present invention,the first characteristic parameter is related to the level information,and a characteristic parameter used for PRACH enhanced sending can berapidly and accurately determined, which reduces power of a terminal.

Another manner for determining the level information of PRACHtransmission and/or PRACH enhanced transmission is as follows: it isdetermined that the level information of PRACH enhanced transmission isthe first (lowest) level of PRACH enhanced transmission. If the UEobtains main information by receiving an enhanced main informationblock, and/or obtains system information by receiving an enhanced systeminformation block, the UE performs preamble sending by using the firstlevel of PRACH enhanced transmission. If the UE fails to perform randomaccess by performing preamble sending by using the n^(th) level of PRACHenhanced transmission, the UE performs preamble sending by using the(n+1)^(th) level of PRACH enhanced transmission, where n is a positiveinteger. The enhanced main information block refers to a maininformation block that is re-sent in a radio frame for multiple times.The enhanced system information block includes one or more of anenhanced system information block of a system information block type 1,an enhanced system information block of a system information block typek, and an enhanced system information block of a system informationblock type m, where k and m are positive integers, and in particular,k=2. The enhanced system information block of the system informationblock type 1 refers to a system information block of the systeminformation block type 1 in a subframe #5 of a radio frame with an evennumber and/or a system information block that is of the systeminformation block type 1 and that is re-sent in another subframe. Theenhanced system information block of the system information block type krefers to a system information block that includes configurationinformation of PRACH enhanced transmission. At least one type ofconfiguration information in configuration information included in thesystem information block of the system information block type m is thesame as configuration information included in the system informationblock of the system information block type 1.

An embodiment of the present invention further provides a networkdevice, as shown in FIG. 4, including: a parameter determining unit 401and a receiving unit 402.

The parameter determining unit 401 is configured to determine a firstcharacteristic parameter that is of PRACH enhanced transmission and thatis related to level information of physical random access channel PRACHenhanced transmission.

In this embodiment of the present invention, the first characteristicparameter may be at least one of a preamble format and a time-frequencyresource.

The receiving unit 402 is configured to perform PRACH enhanced receivingaccording to the first characteristic parameter that is related to alllevel information of PRACH enhanced transmission and that is determinedby the parameter determining unit 401.

Optionally, as shown in FIG. 5, the network device further includes:

a sending unit 501, configured to: before the receiving unit 402performs PRACH enhanced receiving according to the first characteristicparameter related to all the level information of PRACH enhancedtransmission, send, to UE, at least one of the following configurationinformation: preamble initial received target power, a quantity ofpreamble transmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission, and a dedicated power valueof the level information of PRACH enhanced transmission, so that the UEdetermines, according to the configuration information, transmit powerthat is of PRACH enhanced transmission and that is related to the levelinformation of PRACH enhanced transmission, or increase the levelinformation of PRACH enhanced transmission by one level, or execute abackoff operation and perform a preamble resending attempt starting fromlowest level information of PRACH enhanced transmission, or execute abackoff operation and perform a preamble resending attempt by keepingthe level information of PRACH enhanced transmission as highest levelinformation of PRACH enhanced transmission, or adjust a backoffparameter, or notify a higher layer that enhanced random access fails.

Optionally, the parameter determining unit 401 is further configured todetermine that: quantities that are of preamble transmission availableattempt times and that are corresponding to all the level information ofPRACH enhanced transmission are the same, or quantities that are ofpreamble transmission available attempt times and that are correspondingto at least two levels of PRACH enhanced transmission are different.

Optionally, the parameter determining unit 401 is further configured todetermine that dedicated power values of at least two levels of PRACHenhanced transmission in all the level information of PRACH enhancedtransmission are different.

Based on different optional parameters of the first characteristicparameter, there may be different solutions to determining the firstcharacteristic parameter that is of PRACH enhanced transmission and thatis related to the level information of PRACH enhanced transmission, andthis embodiment of the present invention provides a solution, which isspecifically as follows:

Optionally, if the first characteristic parameter includes the preambleformat, the parameter determining unit 401 is configured to determinethat: preamble formats related to all the level information of PRACHenhanced transmission are the same, or preamble formats related to atleast two levels of PRACH enhanced transmission are different.

Optionally, the parameter determining unit 401 is configured to: in aprocess of determining that preamble formats related to at least twolevels of PRACH enhanced transmission are different, if there are Nlevels of PRACH enhanced transmission, determine that: the first N1levels of PRACH enhanced transmission in the N levels of PRACH enhancedtransmission are related to a first preamble format, and subsequent N−N1levels of PRACH enhanced transmission in the N levels of PRACH enhancedtransmission are related to a second preamble format, where both N andN1 are positive integers, N1 is less than N, and the first preambleformat and the second preamble format are different.

Optionally, the parameter determining unit 401 is configured todetermine that the first preamble format and the second preamble formatare preamble formats in a preamble format 1 and a preamble format 3.

Optionally, the parameter determining unit 401 is configured todetermine that a preamble format 4 is not used for PRACH enhancedtransmission.

Optionally, the parameter determining unit 401 is configured todetermine that the preamble format related to the determined levelinformation of PRACH enhanced transmission is predefined; or the sendingunit 501 included in the network device is configured to send, to UE,configuration information of the preamble format related to thedetermined level information of PRACH enhanced transmission.

Optionally, if the first characteristic parameter includes thetime-frequency resource, the parameter determining unit 401 isconfigured to: determine that time-frequency resources related to thefirst M1 levels of PRACH enhanced transmission in M adjacent levels ofPRACH enhanced transmission include a first time-frequency resource; anddetermine that time-frequency resources related to subsequent M−M1levels of PRACH enhanced transmission in the M adjacent levels of PRACHenhanced transmission include a second time-frequency resource, wherethe first time-frequency resource and the second time-frequency resourceare different time-frequency resources, M and M1 are positive integers,and M1 is less than or equal to M.

An embodiment of the present invention further provides a physicalrandom access channel enhanced transmission method, and this method maybe implemented on a network device side. As shown in FIG. 6, the methodincludes the following steps:

601. Determine a first characteristic parameter that is of PRACHenhanced transmission and that is related to level information ofphysical random access channel PRACH enhanced transmission.

In this embodiment of the present invention, the level information maybe any one of a level, a level index, an enhancement level, anenhancement level index, a repetition level, a repetition level index, aresource level, a resource level index, a resource set level, a resourceset level index, a resource set index, and a resource index. In thisembodiment of the present invention, the first characteristic parametermay be at least one of a preamble format and a time-frequency resource.

602. Perform PRACH enhanced receiving according to the firstcharacteristic parameter related to all level information of PRACHenhanced transmission.

Further, before the performing PRACH enhanced receiving according to thefirst characteristic parameter related to all the level information ofPRACH enhanced transmission, the method includes: sending, to UE, atleast one of the following configuration information: preamble initialreceived target power, a quantity of preamble transmission availableattempt times corresponding to the level information of PRACH enhancedtransmission, and a dedicated power value of the level information ofPRACH enhanced transmission, so that the UE determines, according to theconfiguration information, transmit power that is of PRACH enhancedtransmission and that is related to the level information of PRACHenhanced transmission, or increasing the level information of PRACHenhanced transmission by one level, or executing a backoff operation andperforming a preamble resending attempt starting from lowest levelinformation of PRACH enhanced transmission, or executing a backoffoperation and performing a preamble resending attempt by keeping thelevel information of PRACH enhanced transmission as highest levelinformation of PRACH enhanced transmission, or adjusting a backoffparameter, or notifying a higher layer that enhanced random accessfails.

Optionally, quantities that are of preamble transmission availableattempt times and that are corresponding to all the level information ofPRACH enhanced transmission are the same, or quantities that are ofpreamble transmission available attempt times and that are correspondingto at least two levels of PRACH enhanced transmission are different.

Optionally, dedicated power values of at least two levels of PRACHenhanced transmission are different.

Based on different optional parameters of the first characteristicparameter, there may be different solutions to determining the firstcharacteristic parameter that is of PRACH enhanced transmission and thatis related to the level information of PRACH enhanced transmission, andthis embodiment of the present invention provides a solution, which isspecifically as follows:

Optionally, if the first characteristic parameter includes the preambleformat, the determining a first characteristic parameter that is ofPRACH enhanced transmission and that is related to level information ofPRACH enhanced transmission includes:

determining that: preamble formats related to all the level informationof PRACH enhanced transmission are the same, or preamble formats relatedto at least two levels of PRACH enhanced transmission are different.

Optionally, that preamble formats related to at least two levels ofPRACH enhanced transmission are different includes:

if there are N levels of PRACH enhanced transmission, the first N1levels of PRACH enhanced transmission in the N levels of PRACH enhancedtransmission are related to a first preamble format, and subsequent N−N1levels of PRACH enhanced transmission in the N levels of PRACH enhancedtransmission are related to a second preamble format, where both N andN1 are positive integers, N1 is less than N, and the first preambleformat and the second preamble format are different.

Optionally, the first preamble format and the second preamble format arepreamble formats in a preamble format 1 and a preamble format 3.

Optionally, a preamble format 4 is not used for PRACH enhancedtransmission.

Optionally, the preamble format related to the determined levelinformation of PRACH enhanced transmission is predefined; orconfiguration information of the preamble format related to thedetermined level information of PRACH enhanced transmission is sent toUE.

Optionally, if the first characteristic parameter includes thetime-frequency resource, the determining a first characteristicparameter that is of PRACH enhanced transmission and that is related tolevel information of PRACH enhanced transmission includes:

determining that time-frequency resources related to the first M1 levelsof PRACH enhanced transmission in M adjacent levels of PRACH enhancedtransmission include a first time-frequency resource; and determiningthat time-frequency resources related to subsequent M−M1 levels of PRACHenhanced transmission in the M adjacent levels of PRACH enhancedtransmission include a second time-frequency resource, where the firsttime-frequency resource and the second time-frequency resource aredifferent time-frequency resources, M and M1 are positive integers, andM1 is less than or equal to M.

A main problem to be resolved in the present invention is a power wasteof UE caused by an existing power calculation method in PRACH enhancedtransmission. In addition, for different preamble formats, sequenceduration may be different, and for one level of PRACH enhancedtransmission, a quantity of repetition times for resending a preamble isrelated to a preamble format. Therefore, the preamble format that is ofPRACH enhanced transmission and that is related to the level informationof PRACH enhanced transmission may also need to be determined. Thisembodiment of the present invention relates to determining aspects suchas the transmit power, the preamble format, and the time-frequencyresource that are of PRACH enhanced transmission and that are related tothe level information of PRACH enhanced transmission.

Solutions and specific embodiments of the present invention aredescribed by using PRACH enhanced transmission in an LTE or LTE-Asystem, and the PRACH enhanced transmission method provided in thepresent invention may also be applied to another system or channel onwhich resource multiplexing is performed in a CDM manner, such as a CodeDivision Multiple Access (CDMA) system, a Wideband Code DivisionMultiple Access Wireless (WCDMA) system, or a Universal MobileTelecommunication System (UMTS).

With reference to the LTE or LTE-A system, the following describes indetail the PRACH enhanced transmission method provided in thisembodiment of the present invention. In this embodiment of the presentinvention, a PRACH is a channel that carries a preamble; PRACH enhancedtransmission or PRACH transmission may be referred to as enhancedtransmission or transmission of a channel that carries a preamble, ormay be referred to as enhanced transmission or transmission of apreamble. The PRACH enhanced transmission refers to an enhancedtransmission manner such as retransmission or spread spectrumtransmission performed on a preamble. The PRACH transmission refers totransmission performed on a preamble according to an existing formatwithout repetition. Transmission includes sending and receiving. DuringPRACH enhanced transmission, retransmission performed on a preambleaccording to a particular quantity of repetition times or spreadspectrum transmission performed on a preamble according to a particularspreading factor is referred to as one preamble transmission attempt.During PRACH transmission, one time of transmission performed on apreamble is referred to as one preamble transmission attempt. Thesolution in this embodiment of the present invention is described byusing preamble retransmission as an example. The following describes indetail the method in this embodiment of the present invention from a UEside.

First, the level information of PRACH enhanced transmission isdetermined, where the level information is one of a level, a levelindex, an enhancement level, an enhancement level index, a repetitionlevel, a repetition level index, a resource level, a resource levelindex, a resource set level, a resource set level index, a resource setindex, and a resource index. In an LTE or LTE-A system with coverageenhancement, there are multiple levels of PRACH enhanced transmission,and a quantity that is of repetition times for sending a preamble by UEand that is corresponding to each level of PRACH enhanced transmissionis specified in advance by the system or signaled. If the UE determinesthe level information of PRACH enhanced transmission, the UE resends apreamble according to a quantity of repetition times corresponding tothe determined level information of PRACH enhanced transmission. Thelevel information of PRACH enhanced transmission may also be one of aquantity of repetition times, an index of the quantity of repetitiontimes, a coverage enhancement value, a coverage enhancement range index,a path loss, a path loss range index, reference signal received power, areference signal received power range index, reference signal receivedquality, a reference signal received quality range index, channelquality information, and a channel quality information range index.

In this embodiment of the present invention, the level information ofPRACH enhanced transmission may be determined in multiple manners. Itmay also be determined that enhanced transmission is not to be performedon a PRACH, that is, it is determined that PRACH transmission isperformed, where a preamble is sent according to an existing formatwithout repetition. For example, level information of PRACH transmissionand/or the level information of PRACH enhanced transmission may bedetermined according to a path loss range between the UE and a networkside or another measurement parameter or monitoring parameter that canreflect a path loss range; or it is determined that the levelinformation of PRACH enhanced transmission is the first (lowest) levelof PRACH enhanced transmission; or it is determined that the levelinformation of PRACH enhanced transmission is level information obtainedby increasing originally determined level information of PRACH enhancedtransmission by one level of PRACH enhanced transmission; or it isdetermined that PRACH transmission is changed to the first level ofPRACH enhanced transmission. A specific manner for determining the levelinformation of PRACH enhanced transmission is not limited in thisembodiment of the present invention.

One manner for determining the level information of PRACH transmissionand/or PRACH enhanced transmission is as follows: a part of the levelinformation of PRACH transmission and/or PRACH enhanced transmission isdetermined according to the path loss range between the UE and thenetwork side or the another measurement parameter or monitoringparameter that can reflect the path loss range, and other levelinformation of PRACH enhanced transmission is determined by the UE bysequentially performing an attempt from the level information of PRACHtransmission and/or from low level information of enhanced transmissionto high level information of enhanced transmission. If an attempt basedon the level information of PRACH transmission and/or the low levelinformation of enhanced transmission fails, the attempt is switched tobe performed based on an adjacent high level of enhanced transmission.For example, if the level information of PRACH enhanced transmissionincludes the first, the second, and the third level, PRACH transmissionis denoted as the 0^(th) level. If the path loss≤x3 dB, it is determinedthat the level information of PRACH transmission and/or PRACH enhancedtransmission is the 0^(th) level of PRACH transmission; if the pathloss>x4 dB, it is determined that the level information of PRACHtransmission and/or PRACH enhanced transmission is the third level ofPRACH enhanced transmission; if x3 dB<the path loss≤x4 dB, it is firstdetermined that the level information of PRACH transmission and/or PRACHenhanced transmission is the 0^(th) level of PRACH transmission (or thefirst level of PRACH enhanced transmission). If the determining fails,it is determined that the level information of PRACH transmission and/orPRACH enhanced transmission is the first level of a PRACH enhancedtransmission attempt (or the second level of PRACH enhancedtransmission), and so on. In addition, the first characteristicparameter of PRACH enhanced transmission is determined, where the firstcharacteristic parameter of PRACH enhanced transmission is related tothe determined level information of PRACH enhanced transmission, and thefirst characteristic parameter includes one or more of the transmitpower, the preamble format, and the time-frequency resource.

Another manner for determining the level information of PRACHtransmission and/or PRACH enhanced transmission is as follows: it isdetermined that the level information of PRACH enhanced transmission isthe first (lowest) level of PRACH enhanced transmission. If the UEobtains main information by receiving an enhanced main informationblock, and/or obtains system information by receiving an enhanced systeminformation block, the UE performs preamble sending by using the firstlevel of PRACH enhanced transmission. If the UE fails to perform randomaccess by performing preamble sending by using the n^(th) level of PRACHenhanced transmission, the UE performs preamble sending by using the(n+1)^(th) level of PRACH enhanced transmission, where n is a positiveinteger. The enhanced main information block refers to a maininformation block that is re-sent in a radio frame for multiple times.The enhanced system information block includes one or more of anenhanced system information block of a system information block type 1,an enhanced system information block of a system information block typek, and an enhanced system information block of a system informationblock type m, where k and m are positive integers, and in particular,k=2. The enhanced system information block of the system informationblock type 1 refers to a system information block of the systeminformation block type 1 in a subframe #5 of a radio frame with an evennumber and/or a system information block that is of the systeminformation block type 1 and that is re-sent in another subframe. Theenhanced system information block of the system information block type krefers to a system information block that includes configurationinformation of PRACH enhanced transmission. At least one type ofconfiguration information in configuration information included in thesystem information block of the system information block type m is thesame as configuration information included in the system informationblock of the system information block type 1.

Further, PRACH enhanced sending is performed according to the determinedfirst characteristic parameter of PRACH enhanced transmission.

The following describes the present invention in detail by using fourembodiments.

Embodiment 1 of the Present Invention

When the first characteristic parameter of PRACH enhanced transmissionis the transmit power, determining the first characteristic parameter ofPRACH enhanced transmission, where the first characteristic parameter ofPRACH enhanced transmission is related to the determined levelinformation of PRACH enhanced transmission includes:

determining the transmit power of PRACH enhanced transmission accordingto at least a second characteristic parameter corresponding to the levelinformation of PRACH enhanced transmission. The second characteristicparameter includes one or more of preamble initial received targetpower, a quantity of preamble transmission attempt times, a path loss, apath loss threshold, a power ramping step, a power offset value relatedto the preamble format, and a power offset value related to the levelinformation of PRACH enhanced transmission. Second characteristicparameters corresponding to different level information of PRACHenhanced transmission may be completely identical, or partiallyidentical, or completely different. Specifically, there are thefollowing several implementation manners:

Manner 1:

The second characteristic parameter includes the preamble initialreceived target power, the quantity of preamble transmission attempttimes, the path loss, and the power ramping step. Transmit power PPRACHthat is of PRACH enhanced transmission and that is related to the levelinformation of PRACH enhanced transmission that is determined by theUE=min{P_(CMAX,c)(i), PREAMBLE_RECEIVED_TARGET_POWER+PL_(c)}_[dBm],where min{ } indicates an operation for calculating a minimum value,P_(CMAX,c)(i) is a maximum value of transmit power of the UE in asubframe whose number is i, and PL_(c) is the path loss and is a valueestimated by the UE. If the level information of PRACH enhancedtransmission that is determined by the UE is level information obtainedby increasing level information of PRACH enhanced transmission in aprevious preamble sending attempt performed by the UE by one level, orthe 0^(th) level of PRACH transmission is increased to the first levelof PRACH enhanced transmission, and PL_(c) estimated by the UE in theincreased level information of PRACH enhanced transmission isapproximately the same as that estimated for the original levelinformation, and therefore the UE can still use PL_(c) estimated for theoriginal level information. Preamble received target powerPREAMBLE_RECEIVED_TARGET_POWER is equal toPREAMBLE_INITIAL_RECEIVED_TARGET_POWER+(PREAMBLE_TRANSMISSION_COUNTER)−1*powerRampingStep,where PREAMBLE_INITIAL_RECEIVED_TARGET_POWER is the preamble initialreceived target power, and PREAMBLE_TRANSMISSION_COUNTER is the quantityof preamble transmission attempt times. During PRACH enhancedtransmission, each preamble sending attempt includes multiple times ofresending, and a quantity of included resending times is correspondingto the level information of PRACH enhanced transmission that isdetermined by the UE. For each level of PRACH enhanced transmission, aninitial value of the quantity of preamble transmission attempt timesis 1. The initial value is used to perform the first preamble sendingattempt by using one level of PRACH enhanced transmission. After eachpreamble sending attempt is performed, the quantity of preambletransmission attempt times is increased by 1, and powerRampingStep isthe power ramping step and may be a value configured by a base stationby using an SIB2.

If the level information of PRACH enhanced transmission that isdetermined by the UE is not the first level of PRACH enhancedtransmission, where the first level of PRACH enhanced transmission islowest level information of PRACH enhanced transmission, the preambleinitial received target power PREAMBLE_INITIAL_RECEIVED_TARGET_POWERcorresponding to the level information of PRACH enhanced transmissionthat is determined by the UE is determined according to a thirdcharacteristic parameter corresponding to level information that is ofPRACH enhanced transmission and that is one level lower than the levelinformation of PRACH enhanced transmission, where the thirdcharacteristic parameter includes at least one of preamble initialreceived target power, a power ramping step, and a fixed power offsetvalue. Specifically, the preamble initial received target power is equalto a sum of the preamble initial received target power and the powerramping step that are corresponding to the level information that is ofPRACH enhanced transmission and that is one level lower than the levelinformation of PRACH enhanced transmission, or is equal to a sum of thepreamble initial received target power and the power ramping step+afixed power offset value. The power ramping step is a value of(PREAMBLE_TRANSMISSION_COUNTER−1)*powerRampingStep when the UE performsthe last preamble sending attempt before increasing one level of PRACHenhanced transmission.

If the level information of PRACH enhanced transmission that isdetermined by the UE is the first level of PRACH enhanced transmission,the preamble initial received target powerPREAMBLE_INITIAL_RECEIVED_TARGET_POWER corresponding to the levelinformation of PRACH enhanced transmission that is determined by the UEis preambleInitialReceivedTargetPower, wherepreambleInitialReceivedTargetPower is preamble initial received targetpower configured by the base station by using the SIB2, or the preambleinitial received target power corresponding to the level information ofPRACH enhanced transmission that is determined by the UE is a sum ofpreamble initial received target power and a power ramping step that arecorresponding to PRACH transmission, where the power ramping step is avalue of (PREAMBLE_TRANSMISSION_COUNTER−1)*powerRampingStep of thepreamble sending performed for the last time during PRACH transmission(a preamble is not re-sent) performed before PRACH enhancedtransmission, or the preamble initial received target powercorresponding to the level information of PRACH enhanced transmissionthat is determined by the UE is a sum of preamble initial receivedtarget power and a power ramping step that are corresponding to PRACHtransmission+a fixed power offset value.

Manner 2:

The second characteristic parameter includes the preamble initialreceived target power, the quantity of preamble transmission attempttimes, the path loss, and the power ramping step. Transmit power PPRACHthat is of PRACH enhanced transmission and that is related to the levelinformation of PRACH enhanced transmission that is determined by theUE=min{P_(CMAX,c)(i), PREAMBLE_RECEIVED_TARGET_POWER+PL_(c)}_[dBm],where min{ } indicates an operation for calculating a minimum value,P_(CMAX,c)(i) is a maximum value of transmit power of the UE in asubframe whose number is i, and PL_(c) is the path loss and is a valueestimated by the UE. If the level information of PRACH enhancedtransmission that is determined by the UE is level information obtainedby increasing level information of PRACH enhanced transmission in aprevious preamble sending attempt performed by the UE by one level, orthe 0^(th) level of PRACH transmission is increased to the first levelof PRACH enhanced transmission, and PL_(c) estimated by the UE in theincreased level information of PRACH enhanced transmission isapproximately the same as that estimated for the original levelinformation, and therefore the UE can still use PL_(c) estimated for theoriginal level information. Preamble received target powerPREAMBLE_RECEIVED_TARGET_POWER is equal topreambleInitialReceivedTargetPower+(PREAMBLE_TRANSMISSION_COUNTER−1)*powerRampingStep,where preambleInitialReceivedTargetPower is the preamble initialreceived target power, and different from Manner 1,preambleInitialReceivedTargetPower is a value configured by a basestation for the UE by using an SIB2, and for all level information ofPRACH enhanced transmission, corresponding preamble initial receivedtarget power is preambleInitialReceivedTargetPower.PREAMBLE_TRANSMISSION_COUNTER is the quantity of preamble transmissionattempt times, and during PRACH enhanced transmission, each preamblesending attempt includes multiple times of resending, and a quantity ofincluded resending times is corresponding to the level information ofPRACH enhanced transmission that is determined by the UE. After eachpreamble sending attempt is performed, the quantity of preambletransmission attempt times is increased by 1, and powerRampingStep isthe power ramping step and may be a value configured by the base stationby using the SIB2.

Different from Manner 1, if the level information of PRACH enhancedtransmission that is determined by the UE is not the first level ofPRACH enhanced transmission, where the first level of PRACH enhancedtransmission is lowest level information of PRACH enhanced transmission,an initial value of the quantity of preamble transmission attempt timesPREAMBLE_TRANSMISSION_COUNTER corresponding to the level information ofPRACH enhanced transmission that is determined by the UE is determinedaccording to a third characteristic parameter corresponding to levelinformation that is of PRACH enhanced transmission and that is one levellower than the level information of PRACH enhanced transmission, wherethe third characteristic parameter is a maximum quantity of preambletransmission attempt times. The initial value is used to perform thefirst preamble sending attempt by using one level of PRACH enhancedtransmission. Specifically, the initial value of the quantity ofpreamble transmission attempt times PREAMBLE_TRANSMISSION_COUNTERcorresponding to the level information of PRACH enhanced transmissionthat is determined by the UE is equal to 1 plus the maximum quantity ofpreamble transmission attempt times corresponding to the levelinformation that is of PRACH enhanced transmission and that is one levellower than the level information of PRACH enhanced transmission. Themaximum quantity of preamble transmission attempt times corresponding tothe level information that is of PRACH enhanced transmission and that isone level lower than the level information of PRACH enhancedtransmission is a value of a quantity of preamble transmission attempttimes of the last preamble sending attempt performed before the UEincreases one level of PRACH enhanced transmission.

If the level information of PRACH enhanced transmission that isdetermined by the UE is the first level of PRACH enhanced transmission,an initial value of the quantity of preamble transmission attempt timesPREAMBLE_TRANSMISSION_COUNTER corresponding to the level information ofPRACH enhanced transmission that is determined by the UE is equal to 1;or an initial value of the quantity of preamble transmission attempttimes PREAMBLE_TRANSMISSION_COUNTER corresponding to the levelinformation of PRACH enhanced transmission that is determined by the UEis equal to 1 plus a maximum quantity of preamble transmission attempttimes corresponding to PRACH transmission. The maximum quantity ofpreamble transmission attempt times corresponding to PRACH transmissionis a value of a quantity of preamble transmission times of the lastpreamble sending attempt performed during PRACH transmission (a preambleis not re-sent) performed before PRACH enhanced transmission.

Manner 3:

The second characteristic parameter includes the preamble initialreceived target power, the quantity of preamble transmission attempttimes, the path loss or path loss threshold, and the power ramping step.Transmit power PPRACH that is of PRACH enhanced transmission and that isrelated to the level information of PRACH enhanced transmission that isdetermined by the UE=min{P_(CMAX,c)(i),PREAMBLE_RECEIVED_TARGET_POWER+PL_(c)}_[dBm], where min{ } indicates anoperation for calculating a minimum value, P_(CMAX,c)(i) is a maximumvalue of transmit power of the UE in a subframe whose number is i, andPL_(c) is the path loss or path loss threshold. The preamble receivedtarget power PREAMBLE_RECEIVED_TARGET_POWER is equal topreambleInitialReceivedTargetPower+(PREAMBLE_TRANSMISSION_COUNTER−1)*powerRampingStep,where preambleInitialReceivedTargetPower is the preamble initialreceived target power and is a value configured by a base station forthe UE by using an SIB2, and for all level information of PRACH enhancedtransmission, corresponding preamble initial received target power ispreambleInitialReceivedTargetPower. PREAMBLE_TRANSMISSION_COUNTER is thequantity of preamble transmission attempt times, and during PRACHenhanced transmission, each preamble sending attempt includes multipletimes of resending, and a quantity of included resending times iscorresponding to the level information of PRACH enhanced transmissionthat is determined by the UE. For each level of PRACH enhancedtransmission, an initial value of the quantity of preamble transmissionattempt times is 1. The initial value is used to perform the firstpreamble sending attempt by using one level of PRACH enhancedtransmission. After each preamble sending attempt is performed, thequantity of preamble transmission attempt times is increased by 1, andpowerRampingStep is the power ramping step and may be a value configuredby the base station by using the SIB2.

The path loss or path loss threshold PL_(c) is different from that inManner 1 and Manner 2. In Manner 3, the base station or another networkdevice presets a lowest path loss or path loss threshold and a highestpath loss or path loss threshold for determining the level informationof PRACH enhanced transmission, and a path loss between the networkdevice and the UE is divided into X ranges according to the lowest pathloss or path loss threshold and the highest path loss or path lossthreshold, and each path loss range is corresponding to one level ofPRACH enhanced transmission, so that the level information of PRACHenhanced transmission is determined according to the lowest path loss orpath loss threshold and the highest path loss or path loss threshold.For example, a path loss or a path loss threshold is preset to x0, x1,and x2, the path loss between the network device and the UE is dividedinto three ranges, and the first, the second, and the third (or the 1st,the 2nd, and the 3rd) level of PRACH enhanced transmission aredetermined, that is:

the first level of PRACH enhanced transmission: x0 dB<path loss≤x1 dB;

the second level of PRACH enhanced transmission: x1 dB<path loss≤x2 dB;and

the third level of PRACH enhanced transmission: path loss>x2.

For example, for the first level of PRACH enhanced transmission, thelowest path loss or path loss threshold and the highest path loss orpath loss threshold for determining the level information of PRACHenhanced transmission are x0 and x1 respectively. The lowest path lossor path loss threshold and the highest path loss or path loss thresholdand/or a value of X may be predefined or signaled by the network deviceto the UE.

If the level information of PRACH enhanced transmission that isdetermined by the UE is level information obtained by increasing levelinformation of PRACH enhanced transmission in a previous preamblesending attempt performed by the UE by one level, or the levelinformation of PRACH enhanced transmission that is determined by the UEis the first level of PRACH enhanced transmission, and the UE performsPRACH transmission in the previous preamble sending attempt withoutpreamble repetition, in this case, the path loss PL_(c) corresponding tothe level information of PRACH enhanced transmission that is determinedby the UE is the lowest path loss for determining the level informationof PRACH enhanced transmission, or the path loss threshold PL_(c)corresponding to the level information of PRACH enhanced transmissionthat is determined by the UE is the lowest path loss threshold fordetermining the level information of PRACH enhanced transmission. Forexample, if the level information of PRACH enhanced transmission that isdetermined by the UE is the first level of PRACH enhanced transmission,PL_(c) is equal to x0.

If the level information of PRACH enhanced transmission that isdetermined by the UE is not the first level of PRACH enhancedtransmission, the path loss or path loss threshold PL_(c) correspondingto the level information of PRACH enhanced transmission that isdetermined by the UE is a path loss estimated by the UE.

Alternatively, for each level of PRACH enhanced transmission, the pathloss PL_(c) corresponding to the level information of PRACH enhancedtransmission that is determined by the UE is the lowest path loss fordetermining the level information of PRACH enhanced transmission, or thepath loss threshold PL_(c) corresponding to the level information ofPRACH enhanced transmission that is determined by the UE is the lowestpath loss threshold for determining the level information of PRACHenhanced transmission.

Manner 4:

In Manner 4, the second characteristic parameter may further include atleast one of the power offset value related to the preamble format, thepower offset value related to the level information of PRACH enhancedtransmission, and a power offset value of PRACH enhanced transmission.

Accordingly, the preamble received target powerPREAMBLE_RECEIVED_TARGET_POWER is equal topreambleInitialReceivedTargetPower+[DELTAPREAMBLE]−[DELTA_LEVEL]−[DELTA_CI]+(PREAMBLE_TRANSMISSION_COUNTER−1)*powerRampingStep.

Preamble transmit powerPPRACH=min{P_(CMAX,c)(i)−[DELTA_LEVEL]−[DELTA_CI],PREAMBLE_RECEIVED_TARGET_POWER+PL_(c)}_[dBm], where [ ] indicates that aparameter in the square brackets is optional.

DELTA_PREAMBLE is the power offset value related to the preamble formatand is a fixed value, and a value of DELTA_PREAMBLE may be the same asthat in the background. DELTA_CI is the power offset value of PRACHenhanced transmission and is a fixed value, and a value of DELTA_CI maybe specified in a protocol, or may be configured by a network device forthe UE. For all level information of PRACH enhanced transmission, thevalue is the same. DELTA_LEVEL is the power offset value related to thelevel information of PRACH enhanced transmission. Values of otherparameters may be the same as those in the background, or may bedetermined in any one of Manner 1 to Manner 3, which is not limited inthis manner.

In Manner 4, if a base station or another network device presets alowest path loss or path loss threshold and a highest path loss or pathloss threshold for determining the level information of PRACH enhancedtransmission, the level information of PRACH enhanced transmission isdetermined according to the lowest path loss or path loss threshold andthe highest path loss or path loss threshold, a specific method of thedetermining is the same as the description in Manner 3, and details arenot described herein again. A method for determining the power offsetvalue DELTA_LEVEL related to the level information of PRACH enhancedtransmission includes:

setting the power offset value related to the level information of PRACHenhanced transmission to a difference between the highest path loss orpath loss threshold for determining the level information of PRACHenhanced transmission and a path loss estimated by a terminal UE. Forexample, if the level information of PRACH enhanced transmission that isdetermined by the UE is the first level of PRACH enhanced transmission,DELTA_LEVEL=x1−PL_(c), where PL_(c) is the path loss estimated by theUE.

Alternatively, the power offset value related to the level informationof PRACH enhanced transmission is equal to a difference between a sum ofa lowest path loss or path loss threshold for determining the firstlevel of PRACH enhanced transmission and a product that is obtained bymultiplying the level information of PRACH enhanced transmission by apath loss step for determining the level information of PRACH enhancedtransmission and a path loss estimated by a terminal UE. In theforegoing calculation manner, the level information of PRACH enhancedtransmission is a number for indicating level information of PRACHenhanced transmission, and if the level information of PRACH enhancedtransmission is the n^(th) level of PRACH enhanced transmission, thenumber of the level information of PRACH enhanced transmission is equalto n. In this embodiment, the path loss step for determining the levelinformation of PRACH enhanced transmission is equal to a differencebetween the highest path loss (path loss threshold) for determining thelevel information of PRACH enhanced transmission and the lowest pathloss (path loss threshold) for determining the level information ofPRACH enhanced transmission, and for all the level information of PRACHenhanced transmission, path loss steps for determining the levelinformation of PRACH enhanced transmission are the same. For example, ifthe level information of PRACH enhanced transmission that is determinedby the UE is the second level of PRACH enhanced transmission,DELTA_LEVEL=x0+2*(x1−x0)−PL_(c), where PL_(c) is the path loss estimatedby the UE, and x1−x0=x2−x1.

In this embodiment, impact of a near-far effect can be avoided, andpower consumption of the UE can be reduced.

The method in Embodiment 1 further includes a method used by the UE toincrease the level information of PRACH enhanced transmission by onelevel and perform a preamble resending attempt by using increased levelinformation of PRACH enhanced transmission.

Specifically, if the level information of PRACH enhanced transmission isnot highest level information of PRACH enhanced transmission, when thequantity of preamble transmission attempt times corresponding to thelevel information of PRACH enhanced transmission is equal to an initialvalue of the quantity of preamble transmission attempt timescorresponding to the level information of PRACH enhancedtransmission−1+a quantity of preamble transmission available attempttimes corresponding to the level information of PRACH enhancedtransmission, the level information of PRACH enhanced transmission isincreased by one level; or

if the level information of PRACH enhanced transmission is not highestlevel information of PRACH enhanced transmission, when the quantity ofpreamble transmission attempt times corresponding to the levelinformation of PRACH enhanced transmission is equal to a quantity ofpreamble transmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission, the level information ofPRACH enhanced transmission is increased by one level; or

if the level information of PRACH enhanced transmission is highest levelinformation of PRACH enhanced transmission, when the quantity ofpreamble transmission attempt times corresponding to the levelinformation of PRACH enhanced transmission is equal to an initial valueof the quantity of preamble transmission attempt times corresponding tothe level information of PRACH enhanced transmission−1+a quantity ofpreamble transmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission:

(1) A backoff operation is executed and a preamble resending attempt isperformed starting from lowest level information of PRACH enhancedtransmission, which includes selecting a random backoff time based on abackoff (backoff) parameter of the UE, where a value of the backoff timecomplies with a uniform distribution between 0 and a value of thebackoff parameter. The UE delays the backoff time, performs the preambleresending attempt starting from the lowest level information of PRACHenhanced transmission, and recalculates an initial value of the preamblesending attempt. The UE may also include a step of adjusting the backoffparameter.

(2) Alternatively, a backoff operation is executed and a preambleresending attempt is performed by keeping the level information of PRACHenhanced transmission as highest level information of PRACH enhancedtransmission, which includes selecting a random backoff time based on abackoff (backoff) parameter of the UE, where a value of the backoff timecomplies with a uniform distribution between 0 and a value of thebackoff parameter. The UE delays the backoff time, performs the preambleresending attempt by keeping the level information of PRACH enhancedtransmission as the highest level information of PRACH enhancedtransmission, and recalculates an initial value of the preamble sendingattempt. The UE may also include a step of adjusting the backoffparameter.

(3) Alternatively, a backoff parameter is adjusted, that is, the UEadjusts a backoff parameter stored by the UE, where the adjustment maybe increasing or decreasing the backoff parameter by the UE.

(4) Alternatively, the UE notifies a higher layer that enhanced randomaccess fails.

Alternatively, if the level information of PRACH enhanced transmissionis highest level information of PRACH enhanced transmission, when thequantity of preamble transmission attempt times corresponding to thelevel information of PRACH enhanced transmission is equal to a quantityof preamble transmission available attempt times corresponding to thelevel information of PRACH enhanced transmission, a backoff operation isexecuted and a preamble resending attempt is performed starting fromlowest level information of PRACH enhanced transmission, or a backoffoperation is executed, and a preamble resending attempt is performed bykeeping the level information of PRACH enhanced transmission as highestlevel information of PRACH enhanced transmission, or a backoff parameteris adjusted, or the UE notifies a higher layer that enhanced randomaccess fails.

The quantity of preamble transmission available attempt timescorresponding to the level information of PRACH enhanced transmissionrefers to a quantity of times of preamble transmission attempts that canbe performed by using one level of PRACH enhanced transmission, that is,a maximum quantity of preamble transmission available attempt times byusing one level of PRACH enhanced transmission. For different levelinformation of PRACH enhanced transmission, quantities of preambletransmission available attempt times are the same, or quantities thatare of preamble transmission available attempt times and that arecorresponding to at least two levels of PRACH enhanced transmission aredifferent.

The quantity of preamble transmission available attempt timescorresponding to the level information of PRACH enhanced transmissionmay be configured by the base station for the UE by using the SIB2,where a same quantity of preamble transmission available attempt timesmay be configured for all the level information of PRACH enhancedtransmission, or different quantities of preamble transmission availableattempt times may be configured for different level information of PRACHenhanced transmission. Alternatively, the quantity of preambletransmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission is predefined. For example,the quantity of preamble transmission available attempt times isspecified in a protocol. Alternatively, the quantity of preambletransmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission is determined according to apredefined rule. For example, a quantity of preamble transmissionavailable attempt times corresponding to each level of PRACH enhancedtransmission is equal to ┌preambleTransMax/3┐ or ┌preamble TransMax/4┐,where preambleTransMax is a maximum quantity of preamble transmissiontimes configured by the base station, and ┌ ┐ is a round-up operation.

The method in Embodiment 1 further includes a method used by the UE tochange PRACH transmission (the 0^(th) level) into PRACH enhancedtransmission and perform a preamble resending attempt by using the firstlevel of PRACH enhanced transmission.

Specifically, if the quantity of preamble transmission attempt times ofPRACH transmission performed by the UE is equal to an initial value ofthe quantity of preamble transmission attempt times of PRACHtransmission−1+the quantity of preamble transmission available attempttimes of PRACH transmission, PRACH transmission is changed to PRACHenhanced transmission, and the preamble resending attempt is performedby using the first level of PRACH enhanced transmission; or

if the quantity of preamble transmission attempt times of PRACHtransmission performed by the UE is equal to the quantity of preambletransmission available attempt times of PRACH transmission, PRACHtransmission is changed to PRACH enhanced transmission, and the preambleresending attempt is performed by using the first level of PRACHenhanced transmission.

The quantity of preamble transmission available attempt times of PRACHtransmission refers to a quantity of times of preamble transmissionattempts that can be performed during PRACH transmission. The quantityof preamble transmission available attempt times of PRACH transmissionmay be different from an existing preambleTransMax. The quantity ofpreamble transmission available attempt times of PRACH transmission maybe configured by the base station for the UE by using the SIB2, orspecified in a protocol. Optionally, the quantity of preambletransmission available attempt times of PRACH transmission is obtainedby calculating according to the existing preambleTransMax. For example,the quantity of preamble transmission available attempt times of PRACHtransmission is equal to ┌preambleTransMax/4┐.

In this embodiment, when UE resends a preamble according to a quantityof repetition times for increased level information of PRACH enhancedtransmission, the UE ensures continuity of preamble transmit power oforiginal level information of PRACH enhanced transmission, and thereforea probability that power of the first several preamble sending attemptsof the UE cannot meet a requirement for successfully completing a randomaccess process is greatly reduced, which avoids a power waste of the UE.In addition, in Manner 2 of this embodiment, an error caused when thetransmit power is calculated according to a path loss estimated by theUE can also be avoided.

Embodiment 2 of the Present Invention

When the first characteristic parameter of PRACH enhanced transmissionis the transmit power, determining the first characteristic parameter ofPRACH enhanced transmission, where the first characteristic parameter ofPRACH enhanced transmission is related to the determined levelinformation of PRACH enhanced transmission includes: if the levelinformation of PRACH enhanced transmission that is determined by the UEis the n^(th) level of PRACH enhanced transmission, determining that thetransmit power of PRACH enhanced transmission is a maximum value oftransmit power of the UE, where n is an integer greater than 0. Forexample, a value of n may be one or more of 1, 2, and 3 (one, two, andthree), and for example, n is 2 and 3.

In this embodiment, after the UE determines that the level informationof PRACH enhanced transmission is the n^(th) level of PRACH enhancedtransmission, the UE directly performs a preamble sending attemptaccording to the maximum value of the transmit power, which avoids anerror caused when the transmit power is calculated according to a pathloss estimated by the UE.

Considering that on a same time resource and a same frequency resource,the UE sends preambles of different level information of PRACH enhancedtransmission, and if the preambles of the different level information ofPRACH enhanced transmission are sent according to the maximum value ofthe transmit power of the UE, there is a problem of a near-far effect.The method in this embodiment further includes: if the level informationof PRACH enhanced transmission that is determined by the UE is then^(th) level of PRACH enhanced transmission, determining that thetransmit power of PRACH enhanced transmission is a dedicated power valueof the level information of PRACH enhanced transmission.

The dedicated power value of the level information of PRACH enhancedtransmission may be predefined, for example, the dedicated power valueis specified in a protocol; or the dedicated power value of the levelinformation of PRACH enhanced transmission is configured by a basestation, for example, the base station configures the dedicated powervalue for the UE by using an SIB2. Dedicated power values of at leasttwo levels of PRACH enhanced transmission are different. For example,for the at least two levels of PRACH enhanced transmission, a preambleis sent by using a same time-frequency resource, the dedicated powervalues of the at least two levels of PRACH enhanced transmission aredifferent.

In this embodiment, after the UE determines that level information ofPRACH enhanced transmission is the n^(th) level of PRACH enhancedtransmission, the UE directly performs a preamble sending attemptaccording to a dedicated power value of the level information of PRACHenhanced transmission, which avoids an error caused when the transmitpower is calculated according to a path loss estimated by the UE.Further, on a same time-frequency resource, the UE sends preambles ofdifferent level information of PRACH enhanced transmission, and ifdedicated power values used by the preambles of the different levelinformation of PRACH enhanced transmission are different, power valuesof the preambles that are of the different level information of PRACHenhanced transmission and that arrive at a base station areapproximately the same, which avoids impact of a near-far effect.

Embodiment 3 of the Present Invention

For different preamble formats, sequence duration may be different, andfor one level of PRACH enhanced transmission, a quantity of repetitiontimes for resending a preamble is related to a preamble format.Therefore, the preamble format is determined for the level informationof PRACH enhanced transmission in this embodiment.

When the first characteristic parameter of PRACH enhanced transmissionis the preamble format, determining the first characteristic parameterof PRACH enhanced transmission, where the first characteristic parameterof PRACH enhanced transmission is related to the determined levelinformation of PRACH enhanced transmission includes:

determining that preamble formats related to all level information ofPRACH enhanced transmission are the same, or preamble formats related toat least two levels of PRACH enhanced transmission are different.

Within a cell, all the level information of PRACH enhanced transmissionuses a same preamble format. For example, a preamble format 3 is usedfor PRACH enhanced transmission. A method for determining the usedpreamble format is not limited in this embodiment of the presentinvention, and reference may be made to a mature determining solution:that is, the SIB2 sent by the base station includes a physical randomaccess channel configuration index prach-ConfigurationIndex, and the UEdetermines, by using the physical random access channel configurationindex prach-ConfigurationIndex, the preamble format used for randomaccess.

Alternatively, within a cell, the preamble formats related to the atleast two levels of PRACH enhanced transmission are different. Preamblesthat are re-sent according to the at least two levels of PRACH enhancedtransmission use different preamble formats.

In this embodiment, that preamble formats related to at least two levelsof PRACH enhanced transmission are different includes: if there are Nlevels of PRACH enhanced transmission, the first N1 levels of PRACHenhanced transmission in the N levels of PRACH enhanced transmission arerelated to a first preamble format, and subsequent N−N1 levels of PRACHenhanced transmission in the N levels of PRACH enhanced transmission arerelated to a second preamble format, where both N and N1 are positiveintegers, N1 is less than N, and the first preamble format and thesecond preamble format are different. The first preamble format and thesecond preamble format may have same CP duration and different sequenceduration. For example, the first preamble format and the second preambleformat are preamble formats in preamble formats 1 and 3. For example, ifthere are three levels of PRACH enhanced transmission, the first levelof PRACH enhanced transmission is related to the preamble format 1, andthe second level of PRACH enhanced transmission and the third level ofPRACH enhanced transmission are related to the preamble format 3.

In this embodiment, the first N1 levels of PRACH enhanced transmissionin the N levels of PRACH enhanced transmission are adjacent levels, thatis, the first level of PRACH enhanced transmission is successivelyincreased by one level, and increasing is performed for N1−1 times intotal to obtain N1 levels of PRACH enhanced transmission; the subsequentN−N1 levels of PRACH enhanced transmission are adjacent levels, that is,the (N1+1)^(th) level of PRACH enhanced transmission is successivelyincreased by one level, and increasing is performed for N−N1−1 times toobtain N−N1 levels of PRACH enhanced transmission.

The method in this embodiment further includes: a preamble format 4cannot be used for PRACH enhanced transmission. For example, in a TDDsystem with coverage enhancement, the preamble format that is configuredby the base station by using the physical random access channelconfiguration index prach-ConfigurationIndex in the sent SIB2 is not thepreamble format 4.

In this embodiment, the preamble format related to the determined levelinformation of PRACH enhanced transmission may be predefined, forexample, the preamble format is determined in a protocol; or thepreamble format related to the determined level information of PRACHenhanced transmission is configured by the base station for the UE byusing the SIB2. The base station may directly include, in the SIB2, aninformation element (Information Element, IE) or a field for configuringthe preamble format, and configure a same preamble format or differentpreamble formats for the level information of PRACH enhancedtransmission. Alternatively, the base station includes the random accesschannel configuration index prach-ConfigurationIndex in the SIB2, andconfigures a same preamble format or different preamble formats for thelevel information of PRACH enhanced transmission by using the index.

According to the method in this embodiment, a preamble format related tolevel information of PRACH enhanced transmission is determined. Ifpreamble formats related to all level information of PRACH enhancedtransmission are the same, there is a relatively simple random accessimplementation manner. If preamble formats related to at least twolevels of PRACH enhanced transmission are different, one or more levelsof PRACH enhanced transmission may use a preamble format with relativelylong sequence duration, which reduces a CP overhead of a preamble.

Embodiment 4 of the Present Invention

When the first characteristic parameter of PRACH enhanced transmissionis the time-frequency resource, determining the first characteristicparameter of PRACH enhanced transmission, where the first characteristicparameter of PRACH enhanced transmission is related to the determinedlevel information of PRACH enhanced transmission includes: determiningthat time-frequency resources related to the first M1 levels of PRACHenhanced transmission in M adjacent levels of PRACH enhancedtransmission include a first time-frequency resource; and determiningthat time-frequency resources related to subsequent M-M1 levels of PRACHenhanced transmission in the M adjacent levels of PRACH enhancedtransmission include a second time-frequency resource, where the firsttime-frequency resource and the second time-frequency resource aredifferent time-frequency resources, M and M1 are positive integers, andM1 is less than or equal to M. For example, there are three adjacentlevels of PRACH enhanced transmission, a time-frequency resource relatedto the first level of PRACH enhanced transmission includes a currenttime-frequency resource used for PRACH transmission, and time-frequencyresources related to the second level of PRACH enhanced transmission andthe third level of PRACH enhanced transmission include the secondtime-frequency resource, where the second time-frequency resource andthe current time-frequency resource used for PRACH transmission aredifferent. It should be noted that in this embodiment, thattime-frequency resources related to multiple levels of PRACH enhancedtransmission include the first or second time-frequency resource meansthat transmission of random access preambles by using the multiplelevels of PRACH enhanced transmission shares the same first or secondtime-frequency resource, and whether a time-frequency resource differentfrom the shared time-frequency resource may be used for preambletransmission performed by using one level of PRACH enhanced transmissionin the multiple levels of PRACH enhanced transmission is not limited inthis embodiment.

In this embodiment, the first M1 levels of PRACH enhanced transmissionin the M levels of PRACH enhanced transmission are adjacent levels, thatis, the first level of PRACH enhanced transmission is successivelyincreased by one level, and increasing is performed for M1−1 times intotal to obtain M1 levels of PRACH enhanced transmission; the subsequentM-M1 levels of PRACH enhanced transmission are adjacent levels, that is,the (M1+1)^(th) level of PRACH enhanced transmission is successivelyincreased by one level, and increasing is performed for M−M1−1 times toobtain M−M1 levels of PRACH enhanced transmission.

According to the method in this embodiment, because level informationthat is of PRACH enhanced transmission and that is of a preambletransmitted on a same time-frequency resource is an adjacent level, onthe same time-frequency resource, a difference between path losses ofpreambles that are of different level information of PRACH enhancedtransmission and that are sent by UE is limited, and a differencebetween power attenuation values when the preambles arrive at a basestation is limited, and therefore impact of a near-far effect isreduced. In addition, on the same time-frequency resource, if thepreambles of the different level information of PRACH enhancedtransmission use a CDM resource multiplexing manner, a same preambleformat needs to be used, where a first time-frequency resource and asecond time-frequency resource are different time-frequency resources;in this case, subsequent M-M1 levels of PRACH enhanced transmission mayuse a preamble format different from that used by the first M1 levels ofPRACH enhanced transmission, and therefore a preamble format withrelatively long sequence duration may be used, which reduces a CPoverhead of a preamble.

An embodiment of the present invention further provides anotherterminal, as shown in FIG. 7, including: a receiver 701, a transmitter702, a processor 703, and a memory 704.

The processor 703 is configured to: determine level information ofphysical random access channel PRACH enhanced transmission, where inthis embodiment of the present invention, the level information may beany one of a level, a level index, an enhancement level, an enhancementlevel index, a repetition level, a repetition level index, a resourcelevel, a resource level index, a resource set level, a resource setlevel index, a resource set index, and a resource index; and determine afirst characteristic parameter that is of PRACH enhanced transmissionand that is related to the level information of PRACH enhancedtransmission, where in this embodiment of the present invention, thefirst characteristic parameter may be at least one of transmit power, apreamble format, and a time-frequency resource. The transmitter 702 isconfigured to perform PRACH enhanced sending according to the firstcharacteristic parameter.

This embodiment of the present invention is applied to an LTE or LTE-Asystem with coverage enhancement, and there are multiple repetitionlevels of PRACH enhanced transmission, for example, repetition levels 1,2, and 3 of PRACH enhanced transmission. Index numbering may beperformed on the multiple repetition levels, that is, repetition levelindexes. In another manner, there are multiple levels or multipleenhancement levels of PRACH enhanced transmission, and index numberingis performed on the multiple levels, that is, level indexes, or indexnumbering is performed on the multiple enhancement levels, that is,enhancement level indexes. The level information of PRACH enhancedtransmission is any one of the level, the level index, the enhancementlevel, the enhancement level index, the repetition level, and therepetition level index.

For each level of PRACH enhanced transmission, a quantity of repetitiontimes for sending a preamble by UE and a resource set of PRACH enhancedtransmission that are corresponding to each level of PRACH enhancedtransmission are specified in advance by the system or signaled. Theresource set of PRACH enhanced transmission includes one or moreresources of PRACH enhanced transmission. The resources of PRACHenhanced transmission include a code resource (a preamble), a timeresource, and a frequency resource that are used to send the preamble.The time resource and the frequency resource may be collectivelyreferred to as a time-frequency resource. If the UE determines the levelinformation of PRACH enhanced transmission, the UE resends, according toa quantity of repetition times corresponding to the determined levelinformation of PRACH enhanced transmission, a preamble on a resourcethat is of PRACH enhanced transmission and that is included in theresource set of PRACH enhanced transmission. For different levelinformation of PRACH enhanced transmission, quantities of repetitiontimes for sending a preamble by the UE are different. When a requiredsystem coverage enhancement value is larger, a path loss between the UEand a network device is also larger, level information that is of PRACHenhanced transmission and that is required to be used by the UE tosuccessfully complete a random access process is also higher, and thequantity of repetition times for sending the preamble is larger. Becausethere are multiple levels of PRACH enhanced transmission, there are alsomultiple resource sets of PRACH enhanced transmission, and the multipleresource sets are used by the UE to send the preamble according todifferent quantities of repetition times. A PRACH resource set may bereferred to as a resource set level of PRACH enhanced transmission, andone or more resources that are of PRACH enhanced transmission and thatare included in one resource set of PRACH enhanced transmission may bereferred to as one resource level of PRACH enhanced transmission, andindex numbering is separately performed on the resource set, theresource set level, the resource, and the resource level that are ofPRACH enhanced transmission, that is, a resource set index, a resourceset level index, a resource index, and a resource level index that areof PRACH enhanced transmission. The level information of PRACH enhancedtransmission may also be any one of the resource level, the resourcelevel index, the resource set level, the resource set level index, theresource set index, and the resource index. Index numbering is performedon the quantity of repetition times for sending the preamble by the UE,that is, an index of the quantity of repetition times. The levelinformation of PRACH enhanced transmission may also be one of thequantity of repetition times and the index of the quantity of repetitiontimes.

Optionally, the level information of PRACH enhanced transmission isdetermined according to the path loss between the network device and theUE. A base station or another network device presets a lowest path lossor path loss threshold and a highest path loss or path loss thresholdfor determining the level information of PRACH enhanced transmission,and the path loss between the network device and the UE is divided intoX ranges according to the lowest path loss or path loss threshold andthe highest path loss or path loss threshold, and each path loss rangeis corresponding to one level of PRACH enhanced transmission, so thatthe level information of PRACH enhanced transmission is determinedaccording to the lowest path loss or path loss threshold and the highestpath loss or path loss threshold. For example, a path loss or a pathloss threshold is preset to x0, x1, and x2, the path loss between thenetwork device and the UE is divided into three ranges, and the first,the second, and the third (or the 1st, the 2nd, and the 3rd) level ofPRACH enhanced transmission are determined, that is:

the first level of PRACH enhanced transmission: x0 dB<path loss≤x1 dB;

the second level of PRACH enhanced transmission: x1 dB<path loss≤x2 dB;and

the third level of PRACH enhanced transmission: path loss>x2.

For example, for the first level of PRACH enhanced transmission, thelowest path loss or path loss threshold and the highest path loss orpath loss threshold for determining the level information of PRACHenhanced transmission are x0 and x1 respectively. The lowest path lossor path loss threshold and the highest path loss or path loss thresholdand/or a value of X may be predefined or signaled by the network deviceto the UE. Index numbering is performed on the path loss range, that is,a path loss range index. The path loss may also be one of a requiredcoverage enhancement value, reference signal received power, referencesignal received quality, and channel quality information, and indexnumbering is performed on the coverage enhancement value, the referencesignal received power, the reference signal received quality, and achannel quality information range, that is, a coverage enhancement rangeindex, a reference signal received power range index, a reference signalreceived quality range index, and a channel quality information rangeindex. The level information of PRACH enhanced transmission may also beone of the coverage enhancement value, the coverage enhancement rangeindex, the path loss, the path loss range index, the reference signalreceived power, the reference signal received power range index, thereference signal received quality, the reference signal received qualityrange index, the channel quality information, and the channel qualityinformation range index.

In this embodiment of the present invention, the first characteristicparameter is related to the level information, and a characteristicparameter used for PRACH enhanced sending can be rapidly and accuratelydetermined, which reduces power of a terminal.

Based on the three specific optional parameters included in the firstcharacteristic parameter, this embodiment of the present inventionproposes the following four solutions, which are specifically asfollows:

1. Optionally, the first characteristic parameter includes the transmitpower; and

the processor 703 is configured to determine the transmit power of PRACHenhanced transmission according to a second characteristic parametercorresponding to the level information of PRACH enhanced transmission,where the second characteristic parameter is at least one of preambleinitial received target power, a quantity of preamble transmissionattempt times, a path loss, a path loss threshold, a power ramping step,a power offset value related to the preamble format, and a power offsetvalue related to the level information of PRACH enhanced transmission.

Optionally, the processor 703 is configured to determine the transmitpower of PRACH enhanced transmission according to the secondcharacteristic parameter corresponding to the level information of PRACHenhanced transmission, where second characteristic parameterscorresponding to different level information of PRACH enhancedtransmission are completely identical, or partially identical, orcompletely different.

Optionally, the processor 703 is configured to determine, according to athird characteristic parameter corresponding to level information thatis of PRACH enhanced transmission and that is one level lower than thelevel information of PRACH enhanced transmission, the at least oneparameter included in the second characteristic parameter correspondingto the level information of PRACH enhanced transmission, where the thirdcharacteristic parameter is at least one of preamble initial receivedtarget power, a power ramping step, a fixed power offset value, and amaximum quantity of preamble transmission attempt times.

Optionally, the second characteristic parameter includes the preambleinitial received target power; and

the processor 703 is configured to: if the level information of PRACHenhanced transmission is not the first level of PRACH enhancedtransmission, determine that: the preamble initial received target powercorresponding to the level information of PRACH enhanced transmission isa sum of the preamble initial received target power and the powerramping step that are corresponding to the level information that is ofPRACH enhanced transmission and that is one level lower than the levelinformation of PRACH enhanced transmission, or the preamble initialreceived target power corresponding to the level information of PRACHenhanced transmission is a fixed power offset value plus a sum of thepreamble initial received target power and the power ramping step thatare corresponding to the level information that is of PRACH enhancedtransmission and that is one level lower than the level information ofPRACH enhanced transmission; or

if the level information of PRACH enhanced transmission is the firstlevel of PRACH enhanced transmission, determine that: the preambleinitial received target power corresponding to the level information ofPRACH enhanced transmission is preamble initial received target powerconfigured by a network device, or the preamble initial received targetpower corresponding to the level information of PRACH enhancedtransmission is a sum of preamble initial received target power and apower ramping step that are corresponding to PRACH transmission, or thepreamble initial received target power corresponding to the levelinformation of PRACH enhanced transmission is a fixed power offset valueplus a sum of preamble initial received target power and a power rampingstep that are corresponding to PRACH transmission.

Optionally, the second characteristic parameter includes the quantity ofpreamble transmission attempt times; and

the processor 703 is configured to: set an initial value of the quantityof preamble transmission attempt times corresponding to the levelinformation of PRACH enhanced transmission to 1 plus the maximumquantity of preamble transmission attempt times corresponding to thelevel information that is of PRACH enhanced transmission and that is onelevel lower than the level information of PRACH enhanced transmission;or set an initial value of the quantity of preamble transmission attempttimes corresponding to the level information of PRACH enhancedtransmission to 1; or set an initial value of the quantity of preambletransmission attempt times corresponding to the level information ofPRACH enhanced transmission to 1 plus a maximum quantity of preambletransmission attempt times corresponding to PRACH transmission.

Optionally, the second characteristic parameter includes the path lossor the path loss threshold; and

the processor 703 is configured to: set the path loss corresponding tothe level information of PRACH enhanced transmission to a lowest pathloss for determining the level information of PRACH enhancedtransmission; or set the path loss threshold corresponding to the levelinformation of PRACH enhanced transmission to a lowest path lossthreshold for determining the level information of PRACH enhancedtransmission.

Optionally, the second characteristic parameter includes the poweroffset value related to the level information of PRACH enhancedtransmission; and

the processor 703 is configured to: set the power offset value relatedto the level information of PRACH enhanced transmission to a differencebetween a highest path loss or path loss threshold for determining thelevel information of PRACH enhanced transmission and a path lossestimated by a terminal UE; or set the power offset value related to thelevel information of PRACH enhanced transmission to a difference betweena sum of a lowest path loss or path loss threshold for determining thefirst level of PRACH enhanced transmission and a product that isobtained by multiplying the level information of PRACH enhancedtransmission by a path loss step for determining the level informationof PRACH enhanced transmission and a path loss estimated by a terminalUE.

Optionally, the processor 703 is further configured to: if the levelinformation of PRACH enhanced transmission is not highest levelinformation of PRACH enhanced transmission, when the quantity ofpreamble transmission attempt times corresponding to the levelinformation of PRACH enhanced transmission is equal to a sum of adifference between an initial value of the quantity of preambletransmission attempt times corresponding to the level information ofPRACH enhanced transmission and 1 and a quantity of preambletransmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission, increase the levelinformation of PRACH enhanced transmission by one level; or if the levelinformation of PRACH enhanced transmission is not highest levelinformation of PRACH enhanced transmission, when the quantity ofpreamble transmission attempt times corresponding to the levelinformation of PRACH enhanced transmission is equal to a quantity ofpreamble transmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission, increase the levelinformation of PRACH enhanced transmission by one level; or if the levelinformation of PRACH enhanced transmission is highest level informationof PRACH enhanced transmission, when the quantity of preambletransmission attempt times corresponding to the level information ofPRACH enhanced transmission is equal to a sum of a difference between aninitial value of the quantity of preamble transmission attempt timescorresponding to the level information of PRACH enhanced transmissionand 1 and a quantity of preamble transmission available attempt timescorresponding to the level information of PRACH enhanced transmission,execute a backoff operation and perform a preamble resending attemptstarting from lowest level information of PRACH enhanced transmission,or execute a backoff operation and perform a preamble resending attemptby keeping the level information of PRACH enhanced transmission ashighest level information of PRACH enhanced transmission, or adjust abackoff parameter, or notify a higher layer that enhanced random accessfails; or if the level information of PRACH enhanced transmission ishighest level information of PRACH enhanced transmission, when thequantity of preamble transmission attempt times corresponding to thelevel information of PRACH enhanced transmission is equal to a quantityof preamble transmission available attempt times corresponding to thelevel information of PRACH enhanced transmission, execute a backoffoperation and perform a preamble resending attempt starting from lowestlevel information of PRACH enhanced transmission, or execute a backoffoperation and perform a preamble resending attempt by keeping the levelinformation of PRACH enhanced transmission as highest level informationof PRACH enhanced transmission, or adjust a backoff parameter, or notifya higher layer that enhanced random access fails.

Further, the processor 703 is further configured to determine that:quantities that are of preamble transmission available attempt times andthat are corresponding to all level information of PRACH enhancedtransmission are the same, or quantities that are of preambletransmission available attempt times and that are corresponding to atleast two levels of PRACH enhanced transmission are different.

Optionally, the processor 703 is configured to determine that: thequantity of preamble transmission available attempt times correspondingto the level information of PRACH enhanced transmission is configured bythe network device, or the quantity of preamble transmission availableattempt times corresponding to the level information of PRACH enhancedtransmission is predefined, or the quantity of preamble transmissionavailable attempt times corresponding to the level information of PRACHenhanced transmission is determined according to a predefined rule.

2. Optionally, if the first characteristic parameter includes thetransmit power,

the processor 703 is configured to: if the level information of PRACHenhanced transmission is the n^(th) level of PRACH enhancedtransmission, determine that: the transmit power of PRACH enhancedtransmission is a maximum value of transmit power of a terminal UE, orthe transmit power of PRACH enhanced transmission is a dedicated powervalue of the level information of PRACH enhanced transmission, where nis a positive integer.

Optionally, the processor 703 is configured to: determine the dedicatedpower value of the level information of PRACH enhanced transmissionaccording to a predefined value; or

determine the dedicated power value of the level information of PRACHenhanced transmission according to configuration performed by a networkdevice.

Optionally, the processor 703 is configured to determine that dedicatedpower values of at least two levels of PRACH enhanced transmission indedicated power values of the level information of PRACH enhancedtransmission are different.

3. Optionally, if the first characteristic parameter includes thepreamble format,

the processor 703 is configured to determine that: preamble formatsrelated to all level information of PRACH enhanced transmission are thesame, or preamble formats related to at least two levels of PRACHenhanced transmission are different.

Optionally, the processor 703 is configured to: in a process ofdetermining that preamble formats related to at least two levels ofPRACH enhanced transmission are different, if there are N levels ofPRACH enhanced transmission, determine that: the first N1 levels ofPRACH enhanced transmission in the N levels of PRACH enhancedtransmission are related to a first preamble format, and subsequent N−N1levels of PRACH enhanced transmission in the N levels of PRACH enhancedtransmission are related to a second preamble format, where both N andN1 are positive integers, N1 is less than N, and the first preambleformat and the second preamble format are different.

Optionally, the processor 703 is configured to determine that the firstpreamble format and the second preamble format are preamble formats in apreamble format 1 and a preamble format 3.

Optionally, the processor 703 is configured to determine that a preambleformat 4 is not used for PRACH enhanced transmission.

Optionally, the processor 703 is configured to determine that: the usedpreamble format related to the determined level information of PRACHenhanced transmission is predefined, or the preamble format related tothe determined level information of PRACH enhanced transmission isconfigured by a network device.

4. Optionally, the first characteristic parameter includes thetime-frequency resource; and

the processor 703 is configured to: determine that time-frequencyresources related to the first M1 levels of PRACH enhanced transmissionin M adjacent levels of PRACH enhanced transmission include a firsttime-frequency resource; and determine that time-frequency resourcesrelated to subsequent M−M1 levels of PRACH enhanced transmission in theM adjacent levels of PRACH enhanced transmission include a secondtime-frequency resource, where the first time-frequency resource and thesecond time-frequency resource are different time-frequency resources, Mand M1 are positive integers, and M1 is less than or equal to M.

An embodiment of the present invention further provides a networkdevice, as shown in FIG. 8, including: a receiver 801, a transmitter802, a processor 803, and a memory 804.

The processor 803 is configured to determine a first characteristicparameter that is of PRACH enhanced transmission and that is related tolevel information of physical random access channel PRACH enhancedtransmission.

In this embodiment of the present invention, the first characteristicparameter may be at least one of a preamble format and a time-frequencyresource.

The receiver 801 is configured to perform PRACH enhanced receivingaccording to the first characteristic parameter that is related to alllevel information of PRACH enhanced transmission and that is determinedby the processor 803.

Optionally, as shown in FIG. 8, the network device further includes:

the transmitter 802, configured to: before the receiver 801 performsPRACH enhanced receiving according to the first characteristic parameterrelated to all the level information of PRACH enhanced transmission,send, to UE, at least one of the following configuration information:preamble initial received target power, a quantity of preambletransmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission, and a dedicated power valueof the level information of PRACH enhanced transmission, so that the UEdetermines, according to the configuration information, transmit powerthat is of PRACH enhanced transmission and that is related to the levelinformation of PRACH enhanced transmission, or increase the levelinformation of PRACH enhanced transmission by one level, or execute abackoff operation and perform a preamble resending attempt starting fromlowest level information of PRACH enhanced transmission, or execute abackoff operation and perform a preamble resending attempt by keepingthe level information of PRACH enhanced transmission as highest levelinformation of PRACH enhanced transmission, or adjust a backoffparameter, or notify a higher layer that enhanced random access fails.

Optionally, the processor 803 is further configured to determine that:quantities that are of preamble transmission available attempt times andthat are corresponding to all the level information of PRACH enhancedtransmission are the same, or quantities that are of preambletransmission available attempt times and that are corresponding to atleast two levels of PRACH enhanced transmission are different.

Optionally, the processor 803 is further configured to determine thatdedicated power values of at least two levels of PRACH enhancedtransmission in all the level information of PRACH enhanced transmissionare different.

Based on different optional parameters of the first characteristicparameter, there may be different solutions to determining the firstcharacteristic parameter that is of PRACH enhanced transmission and thatis related to the level information of PRACH enhanced transmission, andthis embodiment of the present invention provides a solution, which isspecifically as follows:

Optionally, if the first characteristic parameter includes the preambleformat, the processor 803 is configured to determine that: preambleformats related to all the level information of PRACH enhancedtransmission are the same, or preamble formats related to at least twolevels of PRACH enhanced transmission are different.

Optionally, the processor 803 is configured to: in a process ofdetermining that preamble formats related to at least two levels ofPRACH enhanced transmission are different, if there are N levels ofPRACH enhanced transmission, determine that: the first N1 levels ofPRACH enhanced transmission in the N levels of PRACH enhancedtransmission are related to a first preamble format, and subsequent N−N1levels of PRACH enhanced transmission in the N levels of PRACH enhancedtransmission are related to a second preamble format, where both N andN1 are positive integers, N1 is less than N, and the first preambleformat and the second preamble format are different.

Optionally, the processor 803 is configured to determine that the firstpreamble format and the second preamble format are preamble formats in apreamble format 1 and a preamble format 3.

Optionally, the processor 803 is configured to determine that a preambleformat 4 is not used for PRACH enhanced transmission.

Optionally, the processor 803 is configured to determine that thepreamble format related to the determined level information of PRACHenhanced transmission is predefined; or

the transmitter 802 included in the network device is configured tosend, to UE, configuration information of the preamble format related tothe determined level information of PRACH enhanced transmission.

Optionally, if the first characteristic parameter includes thetime-frequency resource, the processor 803 is configured to: determinethat time-frequency resources related to the first M1 levels of PRACHenhanced transmission in M adjacent levels of PRACH enhancedtransmission include a first time-frequency resource; and determine thattime-frequency resources related to subsequent M−M1 levels of PRACHenhanced transmission in the M adjacent levels of PRACH enhancedtransmission include a second time-frequency resource, where the firsttime-frequency resource and the second time-frequency resource aredifferent time-frequency resources, M and M1 are positive integers, andM1 is less than or equal to M.

An embodiment of the present invention further provides anotherterminal. As shown in FIG. 9, for ease of description, only partsrelated to this embodiment of the present invention are illustrated. Forspecific technical details that are not disclosed, refer to the methodpart of the embodiments of the present invention. The terminal may beany terminal device such as a mobile phone, a tablet computer, a PDA(Personal Digital Assistant, personal digital assistant), a POS (Pointof Sales, point of sales), or a vehicle-mounted computer, for example,the terminal is a mobile phone.

FIG. 9 shows a block diagram of a partial structure of a mobile phonerelated to the terminal provided in this embodiment of the presentinvention. Referring to FIG. 9, the mobile phone includes parts such asa radio frequency (Radio Frequency, RF) circuit 910, a memory 920, aninput unit 930, a display unit 940, a sensor 950, an audio frequencycircuit 960, a wireless fidelity (wireless fidelity, WiFi) module 970, aprocessor 980, and a power supply 990. A person skilled in the art mayunderstand that the mobile phone structure shown in FIG. 9 does notconstitute any limitation to the mobile phone and may include more orless parts than those shown in the figure, or a combination of someparts, or parts disposed differently.

The following describes each constituent part of the mobile phone indetail with reference to FIG. 9:

The RF circuit 910 may be configured to receive and send a signal in aninformation receiving or sending process or a call process, and inparticular, after receiving downlink information of a base station, sendthe downlink information to the processor 980 to perform processing; andin addition, send designed uplink data to the base station. Generally,the RF circuit 910 includes but is not limited to an antenna, at leastone amplifier, a transceiver, a coupler, a low noise amplifier (LowNoise Amplifier, LNA), and a duplexer. In addition, the RF circuit 910may further communicate with a network and another device by means ofradio communication. Any communications standard or protocol may be usedfor the foregoing radio communication, including but not limited to aGlobal System for Mobile Communications (Global System of Mobilecommunication, GSM), a general packet radio service (General PacketRadio Service, GPRS), Code Division Multiple Access (Code DivisionMultiple Access, CDMA), Wideband Code Division Multiple Access (WidebandCode Division Multiple Access, WCDMA), Long Term Evolution (Long TermEvolution, LTE), an email, and a short message service (Short MessagingService, SMS).

The memory 920 may be configured to store a software program and amodule, and the processor 980 runs the software program and the modulethat are stored in the memory 920, so as to execute various functionsand applications of the mobile phone and perform data processing. Thememory 920 may mainly include a program storage area and a data storagearea, where the program storage area may store an operating system, anapplication program required by at least one function (such as a voiceplay function or an image play function), and the like, and the datastorage area may store data (such as audio data and a phone book)created according to use of the mobile phone, and the like. In addition,the memory 920 may include a high-speed random access memory, and mayfurther include a non-volatile memory, for example, at least onemagnetic disk storage device, a flash memory device, or another volatilesolid-state storage device.

The input unit 930 may be configured to receive input digital orcharacter information, and generate key signal input related to usersetting and function control of the mobile phone. Specifically, theinput unit 930 may include a touch panel 931 and another input device932. The touch panel 931 is also referred to as a touchscreen and maycollect a touch operation (such as an operation performed by a user onthe touch panel 931 or near the touch panel 931 by using any properobject or accessory, such as a finger or a stylus) on or near the touchpanel 931, and drive a corresponding connection apparatus according to apreset program. Optionally, the touch panel 931 may include two parts: atouch detection apparatus and a touch controller. The touch detectionapparatus detects a touch orientation of the user, detects a signalbrought by the touch operation, and transfers the signal to the touchcontroller. The touch controller receives touch information from thetouch detection apparatus, converts the touch information into contactcoordinates, and sends the contact coordinates to the processor 980, andcan receive and execute a command sent by the processor 980. Inaddition, the touch panel 931 may be implemented by using multipletypes, such as a resistive type, a capacitive type, an infrared type,and a surface acoustic wave type. In addition to the touch panel 931,the input unit 930 may include the another input device 932.Specifically, the another input device 932 may include but is notlimited to one or more of a physical keyboard, a function key (such as avolume control key or a switch key), a trackball, a mouse, and ajoystick.

The display unit 940 may be configured to display information input bythe user or information provided for the user, and various menus of themobile phone. The display unit 940 may include a display panel 941.Optionally, the display panel 941 may be configured in a form such as aliquid crystal display (Liquid Crystal Display, LCD) or an organiclight-emitting diode (Organic Light-Emitting Diode, OLED). Further, thetouch panel 931 may cover the display panel 941. When detecting a touchoperation on or near the touch panel 931, the touch panel 931 transfersthe touch operation to the processor 980 to determine a type of a touchevent, and then the processor 980 provides corresponding visual outputon the display panel 941 according to the type of the touch event. InFIG. 9, the touch panel 931 and the display panel 941 are configured astwo independent parts to implement input and output functions of themobile phone. However, in some embodiments, the touch panel 931 and thedisplay panel 941 may be integrated to implement the input and outputfunctions of the mobile phone.

The mobile phone may further include at least one sensor 950, such as alight sensor, a motion sensor, or another sensor. Specifically, thelight sensor may include an ambient light sensor and a proximity sensor,where the ambient light sensor may adjust luminance of the display panel941 according to brightness of ambient light, and the proximity sensormay turn off the display panel 941 and/or backlight when the mobilephone moves to an ear. As a type of motion sensor, an accelerometersensor may detect values of acceleration in various directions(generally, three axes); detect, in a still state, a value and adirection of gravity; and be applied to an application that recognizes amobile phone posture (such as screen switching between landscapeorientation and vertical orientation, a related game, and magnetometerposture calibration), a function related to vibration recognition (suchas a pedometer and knocking), and the like. Other sensors such as agyroscope, a barometer, a hygrometer, a thermometer, and an infraredsensor that may also be configured in the mobile phone are not describedherein again.

The audio frequency circuit 960, a loudspeaker 961, and a microphone 962may provide an audio interface between the user and the mobile phone.The audio frequency circuit 960 may transmit, to the loudspeaker 961, anelectrical signal that is obtained after conversion of received audiodata, and the loudspeaker 961 converts the electrical signal into asound signal and outputs the sound signal; in another aspect, themicrophone 962 converts a collected sound signal into an electricalsignal, the audio frequency circuit 960 receives and converts theelectrical signal into audio data and outputs the audio data to theprocessor 980 to perform processing, and then the audio data is sent to,for example, another mobile phone, by using the RF circuit 910, or theaudio data is output to the memory 920 to perform further processing.

WiFi belongs to a short-distance wireless transmission technology. Themobile phone may help, by using the WiFi module 970, the user send andreceive an email, browse a web page, access streaming media, and thelike. The WiFi module 970 provides wireless broadband Internet accessfor the user. Although FIG. 9 shows the WiFi module 970, it may beunderstood that the WiFi module 970 is not a mandatory part of themobile phone, and may completely be omitted as required without changinga scope of the essence of the present invention.

The processor 980 is a control center of the mobile phone and isconnected to each part of the entire mobile phone by using variousinterfaces and lines, and performs, by running or executing the softwareprogram and/or module that is stored in the memory 920 and invoking datastored in the memory 920, various functions of the mobile phone and dataprocessing, so as to perform overall monitoring on the mobile phone.Optionally, the processor 980 may include one or more processing units.Preferably, an application processor and a modem processor may beintegrated into the processor 980, where the application processormainly processes an operating system, a user interface, an applicationprogram, and the like; and the modem processor mainly processes radiocommunication. It may be understood that the foregoing modem processormay also not be integrated into the processor 980.

The mobile phone further includes the power supply 990 (such as abattery) that supplies power to each part. Preferably, the power supplymay be logically connected to the processor 980 by using a powermanagement system, so that functions such as management of charging,discharging, and power consumption are implemented by using the powersupply management system.

Though not shown, the mobile phone may further include a camera, aBluetooth module, and the like, which are not described herein again.

In this embodiment of the present invention, the processor 980 includedin the terminal further has the following functions:

The processor 980 is configured to: determine level information ofphysical random access channel PRACH enhanced transmission, where inthis embodiment of the present invention, the level information may beany one of a level, a level index, an enhancement level, an enhancementlevel index, a repetition level, a repetition level index, a resourcelevel, a resource level index, a resource set level, a resource setlevel index, a resource set index, and a resource index; and determine afirst characteristic parameter that is of PRACH enhanced transmissionand that is related to the level information of PRACH enhancedtransmission, where in this embodiment of the present invention, thefirst characteristic parameter may be at least one of transmit power, apreamble format, and a time-frequency resource. The RF circuit 910 orthe WIFI module 970 is configured to perform PRACH enhanced sendingaccording to the first characteristic parameter.

This embodiment of the present invention is applied to an LTE or LTE-Asystem with coverage enhancement, and there are multiple repetitionlevels of PRACH enhanced transmission, for example, repetition levels 1,2, and 3 of PRACH enhanced transmission. Index numbering may beperformed on the multiple repetition levels, that is, repetition levelindexes. In another manner, there are multiple levels or multipleenhancement levels of PRACH enhanced transmission, and index numberingis performed on the multiple levels, that is, level indexes, or indexnumbering is performed on the multiple enhancement levels, that is,enhancement level indexes. The level information of PRACH enhancedtransmission is any one of the level, the level index, the enhancementlevel, the enhancement level index, the repetition level, and therepetition level index.

For each level of PRACH enhanced transmission, a quantity of repetitiontimes for sending a preamble by UE and a resource set of PRACH enhancedtransmission that are corresponding to each level of PRACH enhancedtransmission are specified in advance by the system or signaled. Theresource set of PRACH enhanced transmission includes one or moreresources of PRACH enhanced transmission. The resources of PRACHenhanced transmission include a code resource (a preamble), a timeresource, and a frequency resource that are used to send the preamble.The time resource and the frequency resource may be collectivelyreferred to as a time-frequency resource. If the UE determines the levelinformation of PRACH enhanced transmission, the UE resends, according toa quantity of repetition times corresponding to the determined levelinformation of PRACH enhanced transmission, a preamble on a resourcethat is of PRACH enhanced transmission and that is included in theresource set of PRACH enhanced transmission. For different levelinformation of PRACH enhanced transmission, quantities of repetitiontimes for sending a preamble by the UE are different. When a requiredsystem coverage enhancement value is larger, a path loss between the UEand a base station is also larger, level information that is of PRACHenhanced transmission and that is required to be used by the UE tosuccessfully complete a random access process is also higher, and thequantity of repetition times for sending the preamble is larger. Becausethere are multiple levels of PRACH enhanced transmission, there are alsomultiple resource sets of PRACH enhanced transmission, and the multipleresource sets are used by the UE to send the preamble according todifferent quantities of repetition times. A PRACH resource set may bereferred to as a resource set level of PRACH enhanced transmission, andone or more resources that are of PRACH enhanced transmission and thatare included in one resource set of PRACH enhanced transmission may becollectively referred to as one resource level of PRACH enhancedtransmission, and index numbering is separately performed on theresource set, the resource set level, the resource, and the resourcelevel that are of PRACH enhanced transmission, that is, a resource setindex, a resource set level index, a resource index, and a resourcelevel index that are of PRACH enhanced transmission. The levelinformation of PRACH enhanced transmission may also be any one of theresource level, the resource level index, the resource set level, theresource set level index, the resource set index, and the resourceindex. Index numbering is performed on the quantity of repetition timesfor sending the preamble by the UE, that is, an index of the quantity ofrepetition times. The level information of PRACH enhanced transmissionmay also be one of the quantity of repetition times and the index of thequantity of repetition times.

In this embodiment of the present invention, the first characteristicparameter is related to the level information, and a characteristicparameter used for PRACH enhanced sending can be rapidly and accuratelydetermined, which reduces power of a terminal.

Based on the three specific optional parameters included in the firstcharacteristic parameter, this embodiment of the present inventionproposes the following four solutions, which are specifically asfollows:

1. Optionally, the first characteristic parameter includes the transmitpower; and

the processor 980 is configured to determine the transmit power of PRACHenhanced transmission according to a second characteristic parametercorresponding to the level information of PRACH enhanced transmission,where the second characteristic parameter is at least one of preambleinitial received target power, a quantity of preamble transmissionattempt times, a path loss, a path loss threshold, a power ramping step,a power offset value related to the preamble format, and a power offsetvalue related to the level information of PRACH enhanced transmission.

Optionally, the processor 980 is configured to determine the transmitpower of PRACH enhanced transmission according to the secondcharacteristic parameter corresponding to the level information of PRACHenhanced transmission, where second characteristic parameterscorresponding to different level information of PRACH enhancedtransmission are completely identical, or partially identical, orcompletely different.

Optionally, the processor 980 is configured to determine, according to athird characteristic parameter corresponding to level information thatis of PRACH enhanced transmission and that is one level lower than thelevel information of PRACH enhanced transmission, the at least oneparameter included in the second characteristic parameter correspondingto the level information of PRACH enhanced transmission, where the thirdcharacteristic parameter is at least one of preamble initial receivedtarget power, a power ramping step, a fixed power offset value, and amaximum quantity of preamble transmission attempt times.

Optionally, the second characteristic parameter includes the preambleinitial received target power; and

the processor 980 is configured to: if the level information of PRACHenhanced transmission is not the first level of PRACH enhancedtransmission, determine that: the preamble initial received target powercorresponding to the level information of PRACH enhanced transmission isa sum of the preamble initial received target power and the powerramping step that are corresponding to the level information that is ofPRACH enhanced transmission and that is one level lower than the levelinformation of PRACH enhanced transmission, or the preamble initialreceived target power corresponding to the level information of PRACHenhanced transmission is a fixed power offset value plus a sum of thepreamble initial received target power and the power ramping step thatare corresponding to the level information that is of PRACH enhancedtransmission and that is one level lower than the level information ofPRACH enhanced transmission; or

if the level information of PRACH enhanced transmission is the firstlevel of PRACH enhanced transmission, determine that: the preambleinitial received target power corresponding to the level information ofPRACH enhanced transmission is preamble initial received target powerconfigured by a network device, or the preamble initial received targetpower corresponding to the level information of PRACH enhancedtransmission is a sum of preamble initial received target power and apower ramping step that are corresponding to PRACH transmission, or thepreamble initial received target power corresponding to the levelinformation of PRACH enhanced transmission is a fixed power offset valueplus a sum of preamble initial received target power and a power rampingstep that are corresponding to PRACH transmission.

Optionally, the second characteristic parameter includes the quantity ofpreamble transmission attempt times; and

the processor 980 is configured to: set an initial value of the quantityof preamble transmission attempt times corresponding to the levelinformation of PRACH enhanced transmission to 1 plus the maximumquantity of preamble transmission attempt times corresponding to thelevel information that is of PRACH enhanced transmission and that is onelevel lower than the level information of PRACH enhanced transmission;or set an initial value of the quantity of preamble transmission attempttimes corresponding to the level information of PRACH enhancedtransmission to 1; or set an initial value of the quantity of preambletransmission attempt times corresponding to the level information ofPRACH enhanced transmission to 1 plus a maximum quantity of preambletransmission attempt times corresponding to PRACH transmission.

Optionally, the second characteristic parameter includes the path lossor the path loss threshold; and

the processor 980 is configured to: set the path loss corresponding tothe level information of PRACH enhanced transmission to a lowest pathloss for determining the level information of PRACH enhancedtransmission; or set the path loss threshold corresponding to the levelinformation of PRACH enhanced transmission to a lowest path lossthreshold for determining the level information of PRACH enhancedtransmission.

Optionally, the second characteristic parameter includes the poweroffset value related to the level information of PRACH enhancedtransmission; and

the processor 980 is configured to: set the power offset value relatedto the level information of PRACH enhanced transmission to a differencebetween a highest path loss or path loss threshold for determining thelevel information of PRACH enhanced transmission and a path lossestimated by a terminal UE; or set the power offset value related to thelevel information of PRACH enhanced transmission to a difference betweena sum of a lowest path loss or path loss threshold for determining thefirst level of PRACH enhanced transmission and a product that isobtained by multiplying the level information of PRACH enhancedtransmission by a path loss step for determining the level informationof PRACH enhanced transmission and a path loss estimated by a terminalUE.

Optionally, the processor 980 is further configured to: if the levelinformation of PRACH enhanced transmission is not highest levelinformation of PRACH enhanced transmission, when the quantity ofpreamble transmission attempt times corresponding to the levelinformation of PRACH enhanced transmission is equal to a sum of adifference between an initial value of the quantity of preambletransmission attempt times corresponding to the level information ofPRACH enhanced transmission and 1 and a quantity of preambletransmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission, increase the levelinformation of PRACH enhanced transmission by one level; or if the levelinformation of PRACH enhanced transmission is not highest levelinformation of PRACH enhanced transmission, when the quantity ofpreamble transmission attempt times corresponding to the levelinformation of PRACH enhanced transmission is equal to a quantity ofpreamble transmission available attempt times corresponding to the levelinformation of PRACH enhanced transmission, increase the levelinformation of PRACH enhanced transmission by one level; or if the levelinformation of PRACH enhanced transmission is highest level informationof PRACH enhanced transmission, when the quantity of preambletransmission attempt times corresponding to the level information ofPRACH enhanced transmission is equal to a sum of a difference between aninitial value of the quantity of preamble transmission attempt timescorresponding to the level information of PRACH enhanced transmissionand 1 and a quantity of preamble transmission available attempt timescorresponding to the level information of PRACH enhanced transmission,execute a backoff operation and perform a preamble resending attemptstarting from lowest level information of PRACH enhanced transmission,or execute a backoff operation and perform a preamble resending attemptby keeping the level information of PRACH enhanced transmission ashighest level information of PRACH enhanced transmission, or adjust abackoff parameter, or notify a higher layer that enhanced random accessfails; or if the level information of PRACH enhanced transmission ishighest level information of PRACH enhanced transmission, when thequantity of preamble transmission attempt times corresponding to thelevel information of PRACH enhanced transmission is equal to a quantityof preamble transmission available attempt times corresponding to thelevel information of PRACH enhanced transmission, execute a backoffoperation and perform a preamble resending attempt starting from lowestlevel information of PRACH enhanced transmission, or execute a backoffoperation and perform a preamble resending attempt by keeping the levelinformation of PRACH enhanced transmission as highest level informationof PRACH enhanced transmission, or adjust a backoff parameter, or notifya higher layer that enhanced random access fails.

Further, the processor 980 is further configured to determine that:quantities that are of preamble transmission available attempt times andthat are corresponding to all level information of PRACH enhancedtransmission are the same, or quantities that are of preambletransmission available attempt times and that are corresponding to atleast two levels of PRACH enhanced transmission are different.

Optionally, the processor 980 is configured to determine that: thequantity of preamble transmission available attempt times correspondingto the level information of PRACH enhanced transmission is configured bythe network device, or the quantity of preamble transmission availableattempt times corresponding to the level information of PRACH enhancedtransmission is predefined, or the quantity of preamble transmissionavailable attempt times corresponding to the level information of PRACHenhanced transmission is determined according to a predefined rule.

2. Optionally, if the first characteristic parameter includes thetransmit power,

the processor 980 is configured to: if the level information of PRACHenhanced transmission is the n^(th) level of PRACH enhancedtransmission, determine that: the transmit power of PRACH enhancedtransmission is a maximum value of transmit power of a terminal UE, orthe transmit power of PRACH enhanced transmission is a dedicated powervalue of the level information of PRACH enhanced transmission, where nis a positive integer.

Optionally, the processor 980 is configured to: determine the dedicatedpower value of the level information of PRACH enhanced transmissionaccording to a predefined value; or determine the dedicated power valueof the level information of PRACH enhanced transmission according toconfiguration performed by a network device.

Optionally, the processor 980 is configured to determine that dedicatedpower values of at least two levels of PRACH enhanced transmission indedicated power values of the level information of PRACH enhancedtransmission are different.

3. Optionally, if the first characteristic parameter includes thepreamble format,

the processor 980 is configured to determine that: preamble formatsrelated to all level information of PRACH enhanced transmission are thesame, or preamble formats related to at least two levels of PRACHenhanced transmission are different.

Optionally, the processor 980 is configured to: in a process ofdetermining that preamble formats related to at least two levels ofPRACH enhanced transmission are different, if there are N levels ofPRACH enhanced transmission, determine that: the first N1 levels ofPRACH enhanced transmission in the N levels of PRACH enhancedtransmission are related to a first preamble format, and subsequent N−N1levels of PRACH enhanced transmission in the N levels of PRACH enhancedtransmission are related to a second preamble format, where both N andN1 are positive integers, N1 is less than N, and the first preambleformat and the second preamble format are different.

Optionally, the processor 980 is configured to determine that the firstpreamble format and the second preamble format are preamble formats in apreamble format 1 and a preamble format 3.

Optionally, the processor 980 is configured to determine that a preambleformat 4 is not used for PRACH enhanced transmission.

Optionally, the processor 980 is configured to determine that: the usedpreamble format related to the determined level information of PRACHenhanced transmission is predefined, or the preamble format related tothe determined level information of PRACH enhanced transmission isconfigured by a network device.

4. Optionally, the first characteristic parameter includes thetime-frequency resource; and

the processor 980 is configured to: determine that time-frequencyresources related to the first M1 levels of PRACH enhanced transmissionin M adjacent levels of PRACH enhanced transmission include a firsttime-frequency resource; and determine that time-frequency resourcesrelated to subsequent M−M1 levels of PRACH enhanced transmission in theM adjacent levels of PRACH enhanced transmission include a secondtime-frequency resource, where the first time-frequency resource and thesecond time-frequency resource are different time-frequency resources, Mand M1 are positive integers, and M1 is less than or equal to M.

An embodiment of the present invention further provides another networkdevice, and the network device may be a base station. As shown in FIG.10, the network device includes:

a transmission interface unit 1001, a main control processing unit 1002,a baseband processing unit 1003, a radio frequency processing unit 1004,and a radio frequency antenna feeder 1005.

The baseband processing unit 1003 is configured to determine a firstcharacteristic parameter that is of PRACH enhanced transmission and thatis related to level information of physical random access channel PRACHenhanced transmission.

In this embodiment of the present invention, the first characteristicparameter may be at least one of a preamble format and a time-frequencyresource.

The radio frequency antenna feeder 1005 is configured to perform PRACHenhanced receiving according to the first characteristic parameter thatis related to all level information of PRACH enhanced transmission andthat is determined by the baseband processing unit 1003.

Optionally, as shown in FIG. 10, the network device further includes:

the radio frequency antenna feeder 1005, configured to: before the radiofrequency antenna feeder 1005 performs PRACH enhanced receivingaccording to the first characteristic parameter related to all the levelinformation of PRACH enhanced transmission, send, to UE, at least one ofthe following configuration information: preamble initial receivedtarget power, a quantity of preamble transmission available attempttimes corresponding to the level information of PRACH enhancedtransmission, and a dedicated power value of the level information ofPRACH enhanced transmission, so that the UE determines, according to theconfiguration information, transmit power that is of PRACH enhancedtransmission and that is related to the level information of PRACHenhanced transmission, or increase the level information of PRACHenhanced transmission by one level, or execute a backoff operation andperform a preamble resending attempt starting from lowest levelinformation of PRACH enhanced transmission, or execute a backoffoperation and perform a preamble resending attempt by keeping the levelinformation of PRACH enhanced transmission as highest level informationof PRACH enhanced transmission, or adjust a backoff parameter, or notifya higher layer that enhanced random access fails.

Optionally, the baseband processing unit 1003 is configured to determinethat: quantities that are of preamble transmission available attempttimes and that are corresponding to all the level information of PRACHenhanced transmission are the same, or quantities that are of preambletransmission available attempt times and that are corresponding to atleast two levels of PRACH enhanced transmission are different.

Optionally, the baseband processing unit 1003 is configured to determinethat dedicated power values of at least two levels of PRACH enhancedtransmission in all the level information of PRACH enhanced transmissionare different.

Based on different optional parameters of the first characteristicparameter, there may be different solutions to determining the firstcharacteristic parameter that is of PRACH enhanced transmission and thatis related to the level information of PRACH enhanced transmission, andthis embodiment of the present invention provides a solution, which isspecifically as follows:

Optionally, if the first characteristic parameter includes the preambleformat, the baseband processing unit 1003 is configured to determinethat: preamble formats related to all the level information of PRACHenhanced transmission are the same, or preamble formats related to atleast two levels of PRACH enhanced transmission are different.

Optionally, the baseband processing unit 1003 is configured to: in aprocess of determining that preamble formats related to at least twolevels of PRACH enhanced transmission are different, if there are Nlevels of PRACH enhanced transmission, determine that: the first N1levels of PRACH enhanced transmission in the N levels of PRACH enhancedtransmission are related to a first preamble format, and subsequent N−N1levels of PRACH enhanced transmission in the N levels of PRACH enhancedtransmission are related to a second preamble format, where both N andN1 are positive integers, N1 is less than N, and the first preambleformat and the second preamble format are different.

Optionally, the baseband processing unit 1003 is configured to determinethat the first preamble format and the second preamble format arepreamble formats in a preamble format 1 and a preamble format 3.

Optionally, the baseband processing unit 1003 is configured to determinethat a preamble format 4 is not used for PRACH enhanced transmission.

Optionally, the baseband processing unit 1003 is configured to determinethat the preamble format related to the determined level information ofPRACH enhanced transmission is predefined; or the radio frequencyantenna feeder 1005 included in the network device is configured tosend, to UE, configuration information of the preamble format related tothe determined level information of PRACH enhanced transmission.

Optionally, if the first characteristic parameter includes thetime-frequency resource, the baseband processing unit 1003 is configuredto: determine that time-frequency resources related to the first M1levels of PRACH enhanced transmission in M adjacent levels of PRACHenhanced transmission include a first time-frequency resource; anddetermine that time-frequency resources related to subsequent M−M1levels of PRACH enhanced transmission in the M adjacent levels of PRACHenhanced transmission include a second time-frequency resource, wherethe first time-frequency resource and the second time-frequency resourceare different time-frequency resources, M and M1 are positive integers,and M1 is less than or equal to M.

An embodiment of the present invention further provides a solution inwhich a half-duplex frequency division duplex (HD-FDD, Half-DuplexFrequency Division Duplex) receiving device performs frame datatransmission, which is specifically as follows:

For the half-duplex frequency division duplex (HD-FDD, Half-DuplexFrequency Division Duplex) receiving device, when the receiving deviceswitches from a downlink subframe to an uplink subframe or switches froman uplink subframe to a downlink subframe, because of problems such asoff/on switching of a frequency oscillator, a power ramp-up of theoscillator, and a propagation delay between a network device and thereceiving device, a phenomenon that sending in an uplink subframeoverlaps with receiving in a downlink subframe adjacent to the uplinksubframe occurs, and therefore a receiver cannot receive data that is inan entire downlink subframe or cannot send data that is in an entireuplink subframe within an overlapping time. In this embodiment,behaviors/a behavior of the receiving device and/or the network deviceare/is specified to resolve data receiving and sending when sending inthe uplink subframe overlaps with receiving in the downlink subframe.

As shown in FIG. 11, four rows of subframes from the top to the bottomare respectively: a downlink subframe for sending data by the networkdevice, a downlink subframe of the receiving device, an uplink subframeof the receiving device, and an uplink subframe for receiving data bythe network device.

As shown in FIG. 12, four rows of subframes from the top to the bottomare respectively: a downlink subframe for sending data by the networkdevice, a downlink subframe of the receiving device, an uplink subframeof the receiving device, and an uplink subframe for receiving data bythe network device.

FIG. 11 and FIG. 12 show a time for skipping sending data that is in anuplink subframe, a downlink propagation delay, and an uplink propagationdelay; another parameter is described in detail in a subsequentembodiment.

For the half-duplex frequency division duplex (HD-FDD, Half-DuplexFrequency Division Duplex) receiving device, when the receiving deviceswitches from a downlink subframe (for example, a downlink subframe #1of the receiving device in FIG. 11) to an adjacent uplink subframe (forexample, an uplink subframe #2 of the receiving device in FIG. 11),because of factors such as off/on adjustment of an operating frequencyperformed by the frequency oscillator, and a propagation delay betweenthe network device and the receiving device, the receiving device needsto stop receiving data in a later part of the downlink subframe (forexample, the downlink subframe #1 of the receiving device in FIG. 11),and prepare to send data of the uplink subframe (for example, the uplinksubframe #2 of the receiving device in FIG. 11). The later part that isof the downlink subframe (for example, the downlink subframe #1 of thereceiving device in FIG. 11) and in which no receiving operation isperformed is referred to as a guard interval. The guard interval isdetermined by factors such as a time for adjusting an operatingfrequency by the frequency oscillator and the propagation delay betweenthe network device and the receiving device. For example, in FIG. 11,the guard interval of the switching from the downlink subframe #1 of thereceiving device to the uplink subframe #2 of the receiving device is asum of the time for adjusting the operating frequency by the frequencyoscillator and an uplink and downlink round-trip propagation delay.

The time for adjusting the operating frequency by the frequencyoscillator includes an off/on switching time of the frequency oscillatorand a power ramp-up time of the frequency oscillator. In an FDD system,receiving a signal and sending a signal are performed by using twodifferent frequency bands. When a half-duplex FDD receiver does not havea frequency duplexer and has only a frequency oscillator, in a processin which the receiver switches from receiving a signal to sending asignal or switches from sending a signal to receiving a signal, thefrequency oscillator needs to adjust an operating frequency of thefrequency oscillator to complete switching of receiving/sending orsending/receiving a signal. To adjust the operating frequency of thefrequency oscillator, the frequency oscillator generally needs to firstturn off the running frequency oscillator, and then restart thefrequency oscillator to adjust the frequency oscillator to a requiredfrequency. After the frequency oscillator is restarted, a power ramp-uptime is further required. As an example of a power ramp-up of thefrequency oscillator, the power ramp-up time of the frequency oscillatormay be a transient period (Transient period), that is, it takes a timeof 20 us in total for the frequency oscillator to reach a requiredthreshold after startup.

The propagation delay between the network device and the receivingdevice refers to a time used to propagate downlink data over a path fromthe network device to the receiving device and/or a time used topropagate uplink data over a path from the receiving device to thenetwork device. For example, the uplink and downlink round-trippropagation delay in FIG. 11 and FIG. 12 refers to a sum of a time ofpropagation over the path from the network device to the receivingdevice and a time of propagation over the path from the receiving deviceto the network device.

Similarly, when the receiving device switches from an uplink subframe(for example, an uplink subframe #4 of the receiving device in FIG. 11)to an adjacent downlink subframe (for example, a downlink subframe #5 ofthe receiving device in FIG. 11), the receiving device skips sendingdata within a guard interval in a later part of the uplink subframe (forexample, the uplink subframe #4 of the receiving device in FIG. 11), andprepares to receive data of the downlink subframe (for example, thedownlink subframe #5 of the receiving device in FIG. 11). Alternatively,the receiving device completes sending data of the uplink subframe (forexample, an uplink subframe #4 of the receiving device in FIG. 12), butskips receiving downlink data within a guard interval in a former partof the downlink subframe (for example, a downlink subframe #5 of thereceiving device in FIG. 12). The guard interval is determined byfactors such as a time for adjusting an operating frequency by thefrequency oscillator and a propagation delay between the network deviceand the receiving device. For example, in FIG. 11 and FIG. 12, the guardinterval of the receiving device that switches from the uplink subframe#4 to the downlink subframe #5 is a difference between the time foradjusting the operating frequency by the frequency oscillator and anuplink and downlink round-trip propagation delay.

Optionally, the network device skips sending downlink data to thereceiving device in the first downlink subframe (for example, a downlinksubframe 1 of the receiving device in FIG. 11) preceding an uplinksubframe (for example, an uplink subframe 2 of the receiving device inFIG. 11), and/or the network device skips sending downlink data to thereceiving device in the first downlink subframe (for example, a downlinksubframe 5 of the receiving device in FIG. 12) following an uplinksubframe (for example, an uplink subframe 4 of the receiving device inFIG. 12).

In conclusion, an embodiment of the present invention provides a framedata transmission solution, including:

when a half-duplex frequency division duplex (HD-FDD) receiving deviceswitches from an uplink subframe to a downlink subframe, skippingreceiving, by the receiving device, data within a guard interval in aformer part of the downlink subframe, or skipping sending data within aguard interval in a later part of the uplink subframe, where the guardinterval is determined by factors/a factor such as a time for adjustingan operating frequency by a frequency oscillator and/or an uplink anddownlink round-trip propagation delay. Optionally, corresponding to ahalf-duplex frequency division duplex (HD-FDD) receiving device, anetwork device skips sending downlink data to the receiving device inthe first subframe preceding an uplink subframe, and/or the networkdevice skips sending downlink data to the receiving device in the firstdownlink subframe following the uplink subframe.

An embodiment of the present invention provides a device, configured asa half-duplex frequency division duplex receiving device, as shown inFIG. 13, including:

a control unit 1301, configured to: when the receiving device switchesfrom an uplink subframe to a downlink subframe, control the receivingdevice to skip receiving data within a guard interval in a former partof the downlink subframe, or to skip sending data within a guardinterval in a later part of the uplink subframe.

In the foregoing solution, when switching from the uplink subframe tothe downlink subframe, the receiving device skips receiving the datawithin the guard interval in the former part of the downlink subframe,or skips sending the data within the guard interval in the later part ofthe uplink subframe.

Optionally, as shown in FIG. 14, the control unit 1301 includes:

a guard interval determining unit 1401, configured to determine theguard interval according to a time for adjusting an operating frequencyby a frequency oscillator and/or an uplink and downlink round-trippropagation delay.

An embodiment of the present invention provides a network device, asshown in FIG. 15, including:

a sending control unit 1501, configured to: control the network deviceto skip sending downlink data to a half-duplex frequency division duplexreceiving device in the first subframe preceding an uplink subframe,and/or control the network device to skip sending downlink data to thehalf-duplex frequency division duplex receiving device in the firstdownlink subframe following the uplink subframe.

In the foregoing solution, the network device skips sending the downlinkdata to the half-duplex frequency division duplex receiving device inthe first subframe preceding the uplink subframe, and/or skips sendingthe downlink data to the half-duplex frequency division duplex receivingdevice in the first downlink subframe following the uplink subframe,which can avoid overlap between sending in the uplink subframe andreceiving in the downlink subframe.

An embodiment of the present invention provides a frame datatransmission method, as shown in FIG. 16, including the following steps:

1601. A half-duplex frequency division duplex receiving device switchesfrom an uplink subframe to a downlink subframe.

1602. When the half-duplex frequency division duplex receiving deviceswitches from the uplink subframe to the downlink subframe, thereceiving device skips receiving data within a guard interval in aformer part of the downlink subframe, or skips sending data within aguard interval in a later part of the uplink subframe.

In the foregoing solution, when switching from the uplink subframe tothe downlink subframe, the receiving device skips receiving the datawithin the guard interval in the former part of the downlink subframe,or skips sending the data within the guard interval in the later part ofthe uplink subframe, which can avoid overlap between sending in theuplink subframe and receiving in the downlink subframe.

Optionally, the guard interval is determined by using a time foradjusting an operating frequency by a frequency oscillator and/or anuplink and downlink round-trip propagation delay.

An embodiment of the present invention further provides another framedata transmission method, as shown in FIG. 17, including the followingsteps:

1701. A network device determines downlink data that needs to be sent.

1702. The network device skips sending the downlink data to ahalf-duplex frequency division duplex receiving device in the firstsubframe preceding an uplink subframe, and/or the network device skipssending the downlink data to the half-duplex frequency division duplexreceiving device in the first downlink subframe following the uplinksubframe.

In the foregoing solution, the network device skips sending the downlinkdata to the half-duplex frequency division duplex receiving device inthe first subframe preceding the uplink subframe, and/or skips sendingthe downlink data to the half-duplex frequency division duplex receivingdevice in the first downlink subframe following the uplink subframe,which can avoid overlap between sending in the uplink subframe andreceiving in the downlink subframe.

An embodiment of the present invention further provides another device,configured as a half-duplex frequency division duplex receiving device,as shown in FIG. 18, including: a receiver 1801, a transmitter 1802, aprocessor 1803, and a memory 1804, where the processor 1803 isconfigured to: when the receiving device switches from an uplinksubframe to a downlink subframe, skip receiving data within a guardinterval in a former part of the downlink subframe, or skip sending datawithin a guard interval in a later part of the uplink subframe.

In the foregoing solution, when switching from the uplink subframe tothe downlink subframe, the receiving device is controlled to skipreceiving the data within the guard interval in the former part of thedownlink subframe, or to skip sending the data within the guard intervalin the later part of the uplink subframe, which can avoid overlapbetween sending in the uplink subframe and receiving in the downlinksubframe.

Optionally, the processor 1803 is configured to determine the guardinterval by using a time for adjusting an operating frequency by afrequency oscillator and/or an uplink and downlink round-trippropagation delay.

An embodiment of the present invention further provides another networkdevice, as shown in FIG. 19, including: a receiver 1901, a transmitter1902, a processor 1903, and a memory 1904, where the processor 1903 isconfigured to: control the network device to skip sending downlink datato a half-duplex frequency division duplex receiving device in the firstsubframe preceding an uplink subframe, and/or control the network deviceto skip sending downlink data to the half-duplex frequency divisionduplex receiving device in the first downlink subframe following theuplink subframe. In the foregoing solution, the network device skipssending the downlink data to the half-duplex frequency division duplexreceiving device in the first subframe preceding the uplink subframe,and/or skips sending the downlink data to the half-duplex frequencydivision duplex receiving device in the first downlink subframefollowing the uplink subframe, which can avoid overlap between sendingin the uplink subframe and receiving in the downlink subframe.

It should be noted that, the apparatus division is merely logicalfunction division, but the present invention is not limited to theforegoing division, as long as corresponding functions can beimplemented. In addition, specific names of the functional units aremerely provided for the purpose of distinguishing the units from oneanother, but are not intended to limit the protection scope of thepresent invention.

In addition, a person of ordinary skill in the art may understand thatall or a part of the steps of the method embodiments may be implementedby a program instructing relevant hardware. The program may be stored ina computer readable storage medium. The storage medium may include: aread-only memory, a magnetic disk, or an optical disc.

The foregoing descriptions are merely exemplary implementation mannersof the present invention, but are not intended to limit the protectionscope of the present invention. Any variation or replacement readilyfigured out by a person skilled in the art within the technical scopedisclosed in the embodiments of the present invention shall fall withinthe protection scope of the present invention. Therefore, the protectionscope of the present invention shall be subject to the protection scopeof the claims.

1. A physical random access channel (PRACH) enhanced receiving method,comprising: determining a characteristic parameter of a PRACH enhancedtransmission, wherein the characteristic parameter is related to levelinformation of the PRACH enhanced transmission, and wherein thecharacteristic parameter comprises at least one of a preamble format anda time-frequency resource; and performing PRACH enhanced receivingaccording to the characteristic parameter related to the levelinformation of the PRACH enhanced transmission.
 2. The method accordingto claim 1, wherein before performing PRACH enhanced receiving accordingto the characteristic parameter related to the level information ofPRACH enhanced transmission, the method further comprises: sending, to aterminal, configuration information comprising a quantity of preambletransmission available attempts associated with the level information ofthe PRACH enhanced transmission, wherein the configuration informationallows the terminal to determine a transmit power of the PRACH enhancedtransmission, and wherein the transmit power is related to the levelinformation of PRACH enhanced transmission.
 3. The method according toclaim 1, wherein a preamble format 4 is not used for the PRACH enhancedtransmission.
 4. A physical random access channel (PRACH) enhancedreceiving apparatus, comprising: a non-transitory memory; a transceiver;and a processor connected to the non-transitory memory and thetransceiver; wherein the non-transitory memory is configured to storeone or more instructions, and the processor is configured to execute theone or more instructions stored in the non-transitory memory to:determine a characteristic parameter of a PRACH enhanced transmission,wherein the characteristic parameter is related to level information ofthe PRACH enhanced transmission, and wherein the characteristicparameter comprises at least one of a preamble format and atime-frequency resource; and perform PRACH enhanced receiving accordingto the characteristic parameter related to the level information of thePRACH enhanced transmission.
 5. The apparatus according to claim 4,wherein processor is further configured to execute the one or moreinstructions stored in the non-transitory memory to: before performingPRACH enhanced receiving according to the characteristic parameterrelated to the level information of the PRACH enhanced transmission,send, to a terminal, configuration information comprising a quantity ofpreamble transmission available attempts associated with the levelinformation of the PRACH enhanced transmission, wherein theconfiguration information allows the terminal to determine a transmitpower of the PRACH enhanced transmission, and wherein the transmit poweris related to the level information of PRACH enhanced transmission. 6.The apparatus according to claim 4, wherein a preamble format 4 is notused for PRACH enhanced transmission.
 7. A physical random accesschannel (PRACH) enhanced receiving apparatus, comprising: a storagemedium including executable instructions; and a processor; wherein theexecutable instructions, when executed by the processor, cause theapparatus to: determine a characteristic parameter of a PRACH enhancedtransmission, wherein the characteristic parameter is related to levelinformation of the PRACH enhanced transmission, and wherein thecharacteristic parameter comprises at least one of a preamble format anda time-frequency resource; and perform PRACH enhanced receivingaccording to the characteristic parameter related to the levelinformation of PRACH enhanced transmission.
 8. The apparatus accordingto claim 7, wherein the executable instructions, when executed by theprocessor, further cause the apparatus to: before performing PRACHenhanced receiving according to the characteristic parameter related tothe level information of PRACH enhanced transmission, send, to aterminal, configuration information comprising a quantity of preambletransmission available attempts associated with the level information ofthe PRACH enhanced transmission, wherein the configuration informationallows the terminal to determine a transmit power of the PRACH enhancedtransmission, and wherein the transmit power is related to the levelinformation of PRACH enhanced transmission.
 9. The apparatus accordingto claim 7, wherein a preamble format 4 is not used for PRACH enhancedtransmission.